terrorist attacks targeting infrastructure in the united ...a_gtd_targeting critical... · critical...

National Consortium for the Study of Terrorism and Responses to Terrorism A Department of Homeland Security Science and Technology Center of Excellence

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TerroristAttacksTargetingCriticalInfrastructureintheUnitedStates,1970‐2015ReporttotheOfficeofIntelligenceandAnalysis,U.S.DepartmentofHomelandSecurityJune2016


Terrorist Attacks Targeting Critical Infrastructure in the United States, 1970-2015

AboutThisReport

TheauthorofthisreportisErinMillerattheUniversityofMaryland.QuestionsaboutthisreportshouldbedirectedtoErinMillerateemiller@umd.edu.ThisresearchwassupportedbytheU.S.DepartmentofHomelandSecuritythroughAwardNumber 2012‐ST‐061‐CS0001‐04‐AMENDMENT4.Theviewsandconclusionscontainedinthisdocumentarethoseoftheauthorsandshouldnotbeinterpretedasnecessarilyrepresentingtheofficialpolicies,eitherexpressedorimplied,oftheU.S.DepartmentofHomelandSecurityorSTART.TheinitialcollectionofdatafortheGlobalTerrorismDatabase(GTD)datawascarriedoutbythePinkertonGlobalIntelligenceServices(PGIS)between1970and1997andwasdonatedtotheUniversityofMarylandin2001.DigitizingandvalidatingtheoriginalGTDdatafrom1970to1997wasfundedbyagrantfromtheNationalInstituteofJusticein2004(PIsGaryLaFreeandLauraDugan;grantnumber:NIJ2002‐DT‐CX‐0001)andin2005aspartoftheSTARTCenterofExcellencebytheDepartmentofHomelandSecurityScienceandTechnologyDirectorate(DHSS&T),OfficeofUniversityPrograms(PIGaryLaFree;grantnumbersN00140510629and2008‐ST‐061‐ST0004).DatacollectionforincidentsthatoccurredbetweenJanuary1998andMarch2008andupdatestotheearlierdatatomakeitconsistentwithnewGTDcodingcriteriawerefundedbytheDHSS&THumanFactors/BehavioralSciencesDivision(HFD)(PIsGaryLaFreeandGaryAckerman;contractnumberHSHQDC‐05‐X‐00482)andconductedbydatabasestaffattheNationalConsortiumfortheStudyofTerrorismandResponsestoTerrorism(START)andtheCenterforTerrorismandIntelligenceStudies(CETIS).ForGTDdatacollectionfromApril2008toOctober2011,STARTpartneredwiththeInstitutefortheStudyofViolentGroups(ISVG),headquarteredatNewHavenUniversity.TheseeffortswerefundedbyagrantfromDHSS&TOfficeofUniversityPrograms,(PIGaryLaFree;grantnumber2008‐ST‐061‐ST0004).BeginningwitheventsthatoccurredinNovember2011,theSTARTConsortiumheadquarteredattheUniversityofMarylandbegancollectingalldatafortheGTDindependently.Sincethen,allGTDcollectionhasbeenjointlyfundedbyDHSS&TOfficeofUniversityPrograms(PIGaryLaFree;grantnumber2012‐ST‐061‐CS0001)andbytheU.S.StateDepartment(PIsGaryLaFreeandErinMiller;contractnumberSAQMMA12M1292).TheGTDnowincludesinformationon141,966terroristattacksfromaroundtheworldfrom1970through2014andcanbeaccesseddirectlyfromtheSTARTwebsite.Inadditiontoongoingdatacollection,effortstoreviewandupdateinformationonterroristattacksintheUnitedStateshavebeensupportedthroughfundingfromtheDHSS&TResilientSystemsDivision(PIGaryLaFree,grantnumber#2009ST108LR0003).Beginningin2009,effortstosupplementGTDdatafortheUnitedStateshaveincludedsystematicallyreviewingnumerouschronologiesofterrorismandpoliticalviolencetoidentifycasesthatqualifyforinclusionintheGTD,aswellasupdatingexistingGTDcaseswithnewinformation.ThisreportfocusesontheU.S.segmentoftheGlobalTerrorismDatabase.



AboutSTART

TheNationalConsortiumfortheStudyofTerrorismandResponsestoTerrorism(START)issupportedinpartbytheScienceandTechnologyDirectorateoftheU.S.DepartmentofHomelandSecuritythroughaCenterofExcellenceprogrambasedattheUniversityofMaryland.STARTusesstate‐of‐the‐arttheories,methodsanddatafromthesocialandbehavioralsciencestoimproveunderstandingoftheorigins,dynamicsandsocialandpsychologicalimpactsofterrorism.Formoreinformation,[email protected].

Citations

Tocitethisreport,pleaseusethisformat:

Miller,Erin.TerroristAttacksTargetingCriticalInfrastructureintheUnitedStates,1970‐2015.CollegePark,MD:START,2016.



ContentsIntroduction.............................................................................................................................................................................................1

DataCollectionMethodology............................................................................................................................................................1

ProcessingGTDSourceDocuments..........................................................................................................................................2

DefiningTerrorism...........................................................................................................................................................................2

GTDVariablesandCoding.............................................................................................................................................................3

MethodologicalConsistency.........................................................................................................................................................3

CriticalInfrastructureClassificationandLimitations.......................................................................................................4

ProfilesofPerpetratorsofTerrorismintheUnitedStates(PPT‐US)........................................................................5

TerroristAttacksonCriticalInfrastructureintheUnitedStates.....................................................................................6

AttackPatternsandLethality......................................................................................................................................................6

TerroristAttacksonCriticalInfrastructureSectors..........................................................................................................8

CommercialFacilitiesSector...................................................................................................................................................8

GovernmentFacilitiesSector...............................................................................................................................................10

HealthcareandPublicHealthSector................................................................................................................................11

FinancialServicesSector.......................................................................................................................................................13

DefenseIndustrialBaseSector............................................................................................................................................14

EmergencyServicesSector...................................................................................................................................................15

EnergySector..............................................................................................................................................................................16

TransportationSystemsSector...........................................................................................................................................17

FoodandAgricultureSector.................................................................................................................................................19

OtherSectors...............................................................................................................................................................................20

Conclusions............................................................................................................................................................................................20


Terrorist Attacks Targeting Critical Infrastructure in the United States, 1970-2015 1

IntroductionThisreportleveragestheGlobalTerrorismDatabase(GTD)toprovideanoverviewofterroristthreatstocriticalinfrastructureintheUnitedStatesbasedonpatternsofterrorismfrom1970to2015.First,IidentifytrendsinterroristattackstargetingcriticalinfrastructureintheUnitedStates,comparedtoterroristattacksagainstothertypesoftargets.Next,IidentifythemostcommonlytargetedtypesofcriticalinfrastructureintheUnitedStates.Throughoutthisanalysis,IhighlighttheperpetratororganizationsthathavehistoricallytargetedcriticalinfrastructureintheUnitedStates,referencingtheProfilesofPerpetratorsofTerrorismintheUnitedStates(PPT‐US)toprovideadditionalcontextaboutthesegroups.Inaddition,foreachofthecriticalinfrastructuresectorsmostimpactedbyterroristattacks,Idescribethetacticsandweaponstypicallyused.ThepurposeofthisreportistoprovideageneralunderstandingofthepotentialthreatsterrorismposestocriticalinfrastructureintheUnitedStates,servingasafoundationforgeneratingquestionsforfutureresearch.Thus,Iconcludewithabriefdiscussionoftopicsthatmaybeofinterestformorein‐depthanalysis.Beforepresentingtheresults,Ibeginwithanoverviewofthedatacollectionmethodologyforthedatasetsreferencedtoproducethisreport.

DataCollectionMethodology1TheGlobalTerrorismDatabaseistheresultofmultipledatacollectioneffortscarriedoutsince1970thathavereliedonpubliclyavailable,unclassifiedsourcematerials,mainlymediaarticlesandelectronicnewsarchives.ThedatathatoriginallycomprisedthecoreoftheGTDfrom1970to1997werecollectedbyPinkertonGlobalIntelligenceServices(PGIS)onhandwrittenindexcards.Beginningin2001,ateamofresearchersattheUniversityofMarylandobtainedtheseoriginalrecordsanddigitizedthem.By2006themaintenanceofthisdatasethadbecomeakeycomponentoftheresearchportfoliodevelopedbytheNationalConsortiumfortheStudyofTerrorismandResponsestoTerrorism(START),andtheGTDteambeganpartneringwithotherorganizationstocarryoutongoingdatacollectionforeventsthattookplaceafter1997.Throughoutthisperiod,STARTresearchersconductedsupplementaldatacollectionprojectstosystematicallycomparetheGTDtoothersourcesofdatatoimproveitscompletenessandworkedtoupdatehistoricaleventdetailswhenpossible.In2012,theGTDteamatSTARTmovedtheprimarydatacollectionefforttoSTARTheadquartersattheUniversityofMaryland.Sincethen,STARThasassumedsoleresponsibilityforallaspectsofthecollectionandmaintenanceoftheGTD.Toaccomplishthis,wedevelopedaninnovativedatacollectionmethodologyfortheGTDthatisbasedonmorethan10yearsofexperienceandlessonslearnedwithrespecttothecomplexitiesandchallengesofsystematicallycollectingvaliddataonterroristattacksworldwide.

1Partsofthissectionwereexcerptedfromthefollowingreports:Miller,Erin.ProfilesofPerpetratorsofTerrorismintheUnitedStates,1970‐2013:FinalReporttoResilientSystemsDivision,DHSScienceandTechnologyDirectorate.CollegePark,MD:START,2014.Miller,Erin.PatternsofTerrorismintheUnitedStates,1970‐2014.CollegePark,MD:START,2015.AdditionalinformationaboutthedatacollectionmethodologycanbefoundontheGTDwebsiteandintheGTDcodebook.



ProcessingGTDSourceDocumentsWithintheevolvingframeworkofnewsmediaandtechnology,START’sobjectiveistoenhancetheefficiency,accuracy,andcompletenessofGTDcollection.Weaccomplishthisbycombiningthestrengthsofbothautomatedandmanualtechniques.Thedatacollectionprocessdrawsonmorethanonemillionmediaarticlesonanytopicpublisheddailyworldwide.Theprocessofidentifyingtherelativelysmallsubsetofthesearticlesthatdescribeterroristattacksbeginswithapplyingcustomizedkeywordfilterstothe“firehose”ofmediaarticlesavailablethroughasubscriptiontotheMetabaseApplicationProgrammingInterface(API)providedbyMoreoverTechnologies,Inc.WesupplementtheEnglish‐languagecontentfromMetabasewitharticlesdownloadedfromtheOpenSourceCenter(www.opensource.gov),whichincludesEnglish‐languagetranslationsofsourcesfrommorethan160countriesinmorethan80languages.Theinitialfiltersisolateapoolofpotentiallyrelevantarticles,approximately200,000permonth.Wereducethissubsetusingmoresophisticatednaturallanguageprocessingandmachinelearningtechniquestoremoveduplicatesandscorethelikelyrelevanceofthearticles.TheGTDteammanuallyreviewsthissecondsubsetofarticles,approximately20,000eachmonth,toidentifytheuniqueeventsthatsatisfytheGTDinclusioncriteria.Finally,thecodingteamreadsthearticlesthatarelinkedtospecificeventsandrecordsthedetailsofeacheventaccordingtothespecificationsoftheGTDCodebook.

DefiningTerrorismTheGTDdefinesterrorismas“thethreatenedoractualuseofillegalforceandviolencebyanon‐stateactortoachieveapolitical,economic,religious,orsocialgoalthroughfear,coercion,orintimidation.”2Tooperationalizethisdefinition,GTDresearchersincludeinthedatabasethoseincidentsthatsatisfyeachofthefollowingmandatoryinclusioncriteria:

Theincidentmustbeintentional,i.e.,theresultofaconsciouscalculationonthepartofaperpetrator.

Theincidentmustentailsomelevelofviolenceorthreatofviolence,includingpropertyviolenceaswellasviolenceagainstpeople.

Theperpetratorsoftheincidentsmustbesub‐nationalactors.Thedatabasedoesnotincludeactsofstateterrorism.

Inaddition,incidentsrecordedintheGTDmustmeetatleasttwoofthefollowinginclusioncriteria:

1. Theactmustbeaimedatattainingapolitical,economic,religious,orsocialgoal.2. Theremustbeevidenceofanintentiontocoerce,intimidate,orconveysomeothermessagetoa

largeraudience(oraudiences)thantheimmediatevictims.3. TheactionmustbeoutsidethepreceptsofInternationalHumanitarianLawinsofarasittargets

non‐combatants.

Giventhatitcanbedifficulttounambiguouslydetermineifaneventsatisfiestheseinclusioncriteria,theGTDrecordsalsoincludeavariableindicatingwhetherornotthereisspecificdoubtthattheinclusion

2NationalConsortiumfortheStudyofTerrorismandResponsestoTerrorism(START).(2015,June).GlobalTerrorismDatabase:Codebook.RetrievedMay11,2016,fromhttps://www.start.umd.edu/gtd/downloads/Codebook.pdf



criteriaaresatisfied.Suchdoubtistypicallyaresultofincompleteorconflictingreportsaboutthecircumstancesoftheattack.Theseattacksareincludedintheanalysispresentedinthisreport.Inaddition,inclusionintheGTDrequiresthatsomekineticactionhasbeentakenonthepartoftheperpetratorstocarryouttheattack.Weinformallyrefertothisasthe“outthedoor”rule,inthattheperpetratorsmustbeontheirwaytocarryouttheattacktobeincludedintheGTD.Oncetheperpetratorsare“outthedoor,”iftheattackfailsorisotherwisethwartedweincludeitinthedatabaseandmarkitasunsuccessful.TheGTDdoesnotincludeplots,conspiracies,orhoaxesthatwerenotactuallyattempted.TheGTDdoesnotincludeviolencethatoccursspontaneously,suchasriotingorviolenceprecipitatedbytheactionsofauthorities(e.g.,policeraid,trafficstop,orarrest).TheGTDalsodoesnotincludenon‐violentactivitysuchaspeacefulprotests,vandalism,orcivildisobedience.

GTDVariablesandCodingTheGTDcodingstrategyreliesonsixcodingteamsthateachspecializesonaparticulardomainoftheGTDCodebook.Thedomainsincludelocation,perpetrators,targets,weaponsandtactics,casualtiesandconsequences,andgeneralinformation.Eachteamiscomprisedofthreetosixundergraduateorgraduatestudentinternsledbyaresearchassistantandisresponsibleforcodingthedomain‐specificvariablesforeacheventintheGTD.Thedomainteamleadersareresponsibleforthetrainingandsupervisionofteammembersandensuringthequalityofthecodeddata.Thisapproachguaranteesthateachpieceofinformationiscodedandreviewedbysomeonewhoisfamiliarwiththeparticularcodingguidelinesforthedomain,aswellastherelevantcontext.Forexample,theperpetratordomainteamwillhavegreaterfamiliaritywithactiveperpetratororganizations,theirnamingconventions,aliases,spellingvariations,factions,andsplinterorganizations,makingthemwell‐suitedtosystematicallyrecordinformationontheorganizationsattributedresponsibilityforanattack.

MethodologicalConsistencyAlthoughthedatacollectionprocessrecentlydevelopedattheUniversityofMarylandhasimprovedtheinternalconsistencyandcomprehensivenessoftheGTD,aswithanyshiftindatacollectionmethodologyitiscriticaltorecognizetheimplicationsforanalysis.Thefirstyearofdatacollectedunderthenewprocess,2012,representsanearly70percentincreaseinthetotalnumberofworldwideterroristattacksover2011.Themagnitudeofthischangeisfarfromuniformacrosscountriesandtheincreaselikelyreflectsrecentpatternsofterrorismincertainlocations.However,itisalsopartlyaresultoftheimprovedefficiencyofthedatacollectionprocess.Theongoingrapidgrowthoftheinternet,andnewsarchivesandaggregatorsinparticular,makesaproductlikeMetabaseavailabletoresearchers,implicitlyimprovingaccesstoagreatervarietyofnationalandlocalsources.TheuseofautomatedapproachestodocumentclassificationallowstheGTDteamtofocusmoretimereviewingonlythosesourcearticlesthatareclassifiedas“relevant”bymachinelearningalgorithms.Asaresult,wehavetheresourcestoleverageamuchbroaderanddeeperpoolofmediasourcesfromaroundtheworld.Despiteconsistencyinourdefinitionofterrorismandinclusioncriteria,thisexponentialgrowthinavailablesourcematerialshasallowedustocollectmorecomprehensivedataonterrorismthananypreviouseffort.TheGTDresearchteamwillcontinuetoevaluatetheimpactofsourceavailabilityontrendsinthedatabasetobetteradviseusersonimportantimplicationsforanalysis.We



willalsocontinuetoworktosupplementtheGTD“legacy”dataonterroristattackssince1970tofurtherimproveitscompleteness.Ingeneral,comparisonsofaggregatestatisticsovertimeandbetweenlocations—andtheirimplicationsforthestateofinternationalsecurityandglobalcounterterrorismefforts—shouldbeinterpretedwithcautionduetoconsiderablevariationintheavailabilityofsourcematerials.However,becausetheavailabilityofsourceinformationpertainingtotheUnitedStateshasalwaysbeenrelativelyrobust,andtheGTDteamhasconductedextensivesupplementaldatacollectioneffortsforincidentsoccurringintheUnitedStates,weexpectthatthemethodologicalartifactsdescribedherehaveaminimalimpactonanalysisdescribedinthisreport.Infact,datafrom1993aretypicallynotincludedintheGTDbecausetheoriginalrecordswerelostinanofficemovebeforethedataweretransferredtoSTART.However,thesupplementaldataforterroristattackstheUnitedStatesin1993aresufficientlyrobustandareincludedinthestatisticsinthisreport.Collectionandrevisionofthedataareongoing,andtheexactnumbersofattackspresentedinthisreportmaychangeslightlyasnewdatabecomeavailable.

CriticalInfrastructureClassificationandLimitationsTheclassificationoftargetsbasedonthecriticalinfrastructuresectorsrecognizedbytheDepartmentofHomelandSecurityisnotpartofthegeneralGTDcollectionprocess.TheGTDdoesincludeatargetclassificationschemethatidentifiesthetypeoftargetattacked,based21differentcategoriesoftargetsthatdonotdirectlyalignwiththecriticalinfrastructuresectors.(SeeTable1foralistingoftheGTDtargettypesandthecriticalinfrastructuresectorsidentifiedbyPresidentialPolicyDirective21:CriticalInfrastructureSecurityandResilience).AspartofthedevelopmentoftheIntegratedUnitedStatesSecurityDatabase(IUSSD)project,analystsatSTARTreviewedallattacksrecordedintheGTDthatoccurredintheUnitedStatesandclassifiedthembasedonthecriticalinfrastructuresectorsusingavailabletargetdescriptors.FormanyoftheterroristattacksintheUnitedStates,thisclassificationprocesswasrelativelystraightforward.Forexample,attacksagainstentitiesclassifiedasairportsandaircraft,maritime,ortransportationtargetsintheGTDcorrespondtotheTransportationSystemsSector.However,targetsthatwerecategorizedasbusinessesusingtheGTDclassificationschememayfitmostappropriatelyintheCommercialFacilitiesSector,theFinancialServicesSector,ortheFoodandAgricultureSector,amongothers.Finally,certaintypesoftargetsrecognizedintheGTDrepresententitiesthatdonotqualifyastypesofcriticalinfrastructure.Theseincludedmostcommonly:privatecitizensandproperty,educationalinstitutions,religiousfiguresandinstitutions,andjournalistsandmedia.Oureffortstoclassifytargetsbasedonthecriticalinfrastructuresectorsaccommodatedonlyonesectorperattack,whichforthemostpartwassufficient.Lessthan4percentofallattacksthattookplaceintheUnitedStatesinvolvedmorethanonetarget.However,therewereasmallnumberofattacksforwhichthispracticepresentsalimitation.Forexample,thefourattacksonSeptember11,2001eachconceivablytargetedmultiplecriticalinfrastructuresectors,includingtheCommercialFacilitiesSector,theDefenseIndustrialBaseSector,theFinancialServicesSector,theGovernmentFacilitiesSector,andtheTransportationSystemsSector.Althoughperhapsnotdirectlytargeted,othersectorswerecertainlyimpactedbytheseattacksaswell,includingmostnotablytheEmergencyServicesSector.Notethatwe



classifiedtheSeptember11thattackinwhichahijackedcommercialaircraftcrashedintothePentagonasanattackontheDefenseIndustrialBaseSector,andweclassifiedthoseinwhichhijackedcommercialaircraftcrashedinNewYorkCityandnearShanksville,PennsylvaniaasattacksontheTransportationSystemsSector.

Table1:GTDTargetTypesandCriticalInfrastructureSectors

GTDTargetTypes CriticalInfrastructureSectorsAbortion Related Chemical Sector Airports & Aircraft Commercial Facilities Sector Business Communications Sector Educational Institution Critical Manufacturing Sector Food or Water Supply Dams Sector Government (Diplomatic) Defense Industrial Base Sector Government (Non-Diplomatic) Emergency Services Sector Journalists & Media Energy Sector Maritime Vessels Financial Services Sector Military Food and Agriculture Sector

NGO Government Facilities Sector

Other Healthcare and Public Health Sector Police Information Technology Sector Private Citizens & Property Nuclear Reactors, Materials, and Waste Sector Religious Figures/Institutions Transportation Systems Sector Telecommunication Systems Water and Wastewater Systems Sector Terrorists/Non-State Militia Tourists Transportation Utilities Violent Political Party

ProfilesofPerpetratorsofTerrorismintheUnitedStates(PPT‐US)ProfilesofPerpetratorsofTerrorismintheUnitedStates(PPT‐US)isacomprehensivedatasetincludingstructureddatacollectedfromunclassifiedsourceson143organizationsthatcarriedoutterroristattacksintheUnitedStatesbetween1970and2015.Thedatabasecontainsmorethan100variablespertainingtotheorganizations’historicalcontextsandphilosophicalmotivations,ideologies,goals,operations,structures,andfundingsources.PPT‐USalsoincludesreferencestosourcematerialsandconfidencelevelsforeachdatapointtoallowuserstobetterassessthevalidityofinformationthatisoftendifficulttoverify.ThePPT‐USdataandsupportingdocumentationaremadeavailabletothepublictoprovideanalystswitharesourceforinvestigatingthecharacteristicsofperpetratorgroupsthathavecarriedoutterroristattacksintheUnitedStates.GroupsareincludedinPPT‐USiftheyhaveconductedatleastoneterroristattackintheUnitedStates(includingPuertoRico)since1970basedonthedefinitionofterrorismusedintheGTD.Thatis,any



groupidentifiedintheGTDasaperpetratorofanattacktargetingtheU.S.homelandisincludedinPPT‐US.Notethatgroupsthoughttobesuspicious,dangerous,orknowntoespouseextremistideologybutthathavenevercarriedoutaterroristattackagainsttheUnitedStatesareomittedfromPPT‐US.AlsoPPT‐USincludesonlynamedorganizations.Individualperpetratorsofterroristattacksnotaffiliatedwithanamedorganizationarenotincludedinthedataset.Finally,groupsthathavetargetedU.S.interestsabroad,butnotcarriedoutattacksonU.S.soil,arenotincluded.AdditionalcriteriaweredevelopedforincludinganorganizationinPPT‐US:First,theGTDincludesavariablethatindicatesifthereisuncertaintyamongthecodersaboutwhetherthatincidentshouldbeclassifiedasterrorismor,instead,whetheritwouldbemoreproperlyclassifiedasanothertypeofviolence(e.g.,insurgency,inter‐orintra‐groupconflict,orconventionalcrime).Ifsuchuncertaintyexistsforallofaparticulargroup’sactivities,thegroupisexcludedfromPPT.Inaddition,whenattributingresponsibilityforspecificincidentsintheGTDtoorganizations,theGTDteamrecordswhetherthereishighconfidencethatanorganizationis,infact,responsiblefortheattackor,conversely,whetherthegroupisonlythesuspectedperpetrator.OnlyGTDgroupsforwhichthereishighconfidenceofresponsibilityforatleastoneattackareincludedinPPT‐US.Byapplyingtheseselectioncriteria,143groupsresponsibleformorethan1,250terroristattacksintheUnitedStatesbetween1970and2015areincludedinPPT‐US.

TerroristAttacksonCriticalInfrastructureintheUnitedStates

AttackPatternsandLethalityFigure1:TotalterroristattacksandattackstargetingcriticalinfrastructureintheUnitedStatesbyyear,1970‐2015

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Total Attacks (n=2,273)Attacks Targeting Critical Infrastructure (n=2,055)Percent of Attacks Targeting Critical InfrastructureSource: Global Terrorism Database



Between1970and2015,2,723terroristattackstookplaceintheUnitedStates,causingatotalof3,570deaths;ofthese,2,055attacks(75%)targetedcriticalinfrastructure.Figure1illustratesthatthepatternofattacksthattargetedcriticalinfrastructurewasconsistentwiththepatternofattacksoverall.Thatis,thefrequencyofattackswashighestinthe1970s—inparticular,one‐third(34%)ofallattacksoncriticalinfrastructuretookplacebetween1970and1974—anddeclinedgraduallythroughoutthe1980s,1990s,and2000s.The668terroristattacksthatdidnottargetcriticalinfrastructureinvolvedavarietyoftargettypes,butmostfrequentlythesetargetswereclassifiedasprivatecitizensandproperty(38%),educationalinstitutions(24%),religiousfiguresandinstitutions(16%),andjournalistandmedia(9%).Theimpactofterroristattacksoncriticalinfrastructureisinherentlydisruptive;however,thelethalityoftheseattacksalsocloselymirroredthelethalityofattacksintheUnitedStatesmoregenerally.Inparticular,thevastmajorityofterroristattacksintheUnitedStatesbetween1970and2015werenon‐lethal,withafewexceptionsinwhichattackswereextraordinarilydeadly.Infact,89percentofalldeathsduetoterroristattacksintheUnitedStatesduringthistimeperiodwerecausedbythe1995bombingoftheAlfredP.MurrahFederalBuildinginOklahomaCity(5%)andtheSeptember11,2001attacks(84%).Terroristattacksoncriticalinfrastructurewerealsoparadoxicallylesslikelytobedeadlyandmorelikelytobehighlydeadlythanattacksthatdidnottargetcriticalinfrastructure.AsshowninTable2,morethan90percentofallattacksthattargetedcriticalinfrastructurewerenon‐lethal,comparedtojustover80percentofattacksthatdidnottargetcriticalinfrastructure.Incontrast,15percentofattacksthatdidnottargetcriticalinfrastructureresultedinasingledeath,comparedto5percentofattacksthatdidtargetcriticalinfrastructure.

Table2:LethalityofTerroristAttacksintheUnitedStates,1970‐2015

Thereareanumberofreasonsanattackmaybenon‐lethal,includingthepossibilitythatitwasattempted,butunsuccessful—eithertheattackfailedonitsownorwasthwartedbyothers.Inothercasestheattackwasnotintendedtobedeadly,butinsteadtocausepropertydamageratherthanlossof

Total Number of Deaths Attacks Targeting

Critical Infrastructure Attacks Not Targeting Critical Infrastructure

Number Percent Number Percent

0 1854 93.3% 534 81.5%

1 90 4.5% 96 14.7%

2‐4 31 1.6% 20 3.1%

5‐10 4 0.2% 4 0.6%

11‐150 4 0.2% 1 0.1%

>150 4 0.2% 0 0.0%

Total 1986 100.00% 655 100.00%

Note: Total number of deaths is unknown for 3% of all attacks in the United States.

Source: Global Terrorism Database



life.Inlightofthis,thediscrepancyherebetweenattacksthattargetedcriticalinfrastructureandthosethatdidnotmayreflectatendencyforattacksagainstprivatecitizensandproperty,educationalinstitutions,religiousfiguresandinstitutions,andjournalistsandthemediatotargetspecificindividualsratherthanbuildingsorplaceswherelargenumbersofpeoplecongregate.Althoughrelativelyfewattacksoverallresultedinmorethan10deaths,thosethatdidweredisproportionatelylikelytotargetcriticalinfrastructure.

TerroristAttacksonCriticalInfrastructureSectorsAmongtheterroristattacksthatdidtargetcriticalinfrastructure,certainsectorswereimpactedmorethanothers.Between1970and2015,morethantwo‐thirds(68%)ofallattacksoncriticalinfrastructureintheUnitedStatestargetedthecommercialfacilities(22%),governmentfacilities(21%),healthcareandpublichealth(14%),andfinancialservices(11%)sectors.Figure2showsthedistributionofallattacksacrosscriticalinfrastructuresectors,eachofwhichIdiscussingreaterdetailbelow.

Figure2:TerroristAttacksonCriticalInfrastructureintheUnitedStates,1970‐2015(n=2,055)

CommercialFacilitiesSectorThecommercialfacilitiessectorsufferedthehighestnumberofattacksbetween1970and2015,with454attacks,causing39totaldeaths.NotethatthisdoesnotincludetheimplicationsoftheSeptember11,2001attacksonthecommercialfacilitiessector.Asnotedabove,theseattackswereclassifiedashavingtargetedthetransportationsystemsanddefenseindustrialbasesectors.Attacksoncommercialfacilitiestookplaceeachyearbetween1970and2015,withthesoleexceptionof2007.

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Thevastmajority(95%)ofattacksoncommercialfacilitieswerenon‐lethal,andthedeadliestattacktookplacein1973,whensevenvictimsandoneassailant,ablacknationalist,werekilledinanattackatahotelinNewOrleans,Louisiana.Whilemostattacksoncommercialfacilitieswerenon‐lethal,morethan1,500peoplewerewoundedinsuchattacksbetween1970and2015.Theseincludethe1993bombingattheWorldTradeCenterinNewYorkCity,whichinjuredatleast1,000people;the2014bombingsattheBostonMarathoninMassachusetts,whichinjuredmorethan260people;andthe1996bombingatCentennialOlympicParkinAtlanta,Georgia,whichinjuredmorethan100people.Inaddition,89percentoftheterroristattacksoncommercialfacilitiesresultedinsomepropertydamage.AsFigure3shows,thecommercialfacilitiestargetedwerenearlyallclassifiedasbusinesses(86%),includingmostfrequentlyretailstores(36%ofallattacksoncommercialfacilities),industrialfacilitiesorfactories(12%),entertainment,culturalorsportsvenues(10%),andhotels(5%).Theremainingtargetswereverydiverse,eachcomprisinglessthan5percentofthetotal.

Figure3:TypesofCommercialFacilitiesTargetedintheUnitedStates,1970‐2015(n=454)

Thetacticsusedintheseattackswereprimarilybombings(55%)andfacility/infrastructureattacks(40%),inwhichtheprimaryobjectiveistocausedamagetonon‐humantargets,excludingtheuseofexplosives.Facilityattackstypicallyinvolvearson.Lessthan3percentoftheattacksoncommercialfacilitieswerearmedassaults;andkidnappings,barricadeincidents,unarmedassaults,assassinationseachcomprisedlessthan1percentofthetotal.

Other37%

Retail36%

Industrial/ Factories12%

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Hotels/Resorts5%




Fornearlyone‐fifth(19%)oftheterroristattacksoncommercialfacilitiesintheUnitedStatesbetween1970and2015noinformationabouttheperpetrator(s)wasreportedinsourcematerials.Amongtheremainingcases,morethan70perpetratororganizationsandgenericdesignations(e.g.,“CubanExiles”)wereidentified,aswellasunaffiliatedindividualperpetrators.ThetwoorganizationsresponsibleforthemostattacksweretheEarthLiberationFront(11%)andtheAnimalLiberationFront(9%),whichwereprimarilyactiveinthe1990sand2000s.TwoPuertoRicanindependencegroupsactiveinthe1970s—FuerzasArmadasdeLiberacionNacional(FALN)andtheArmedRevolutionaryIndependenceMovement(MIRA)—followed,with8percentand7percent,respectively.Theremainingattackswerecarriedoutbygroupsandorganizationsrepresentingavarietyofideologicalinfluences,includingleft‐wingextremists,right‐wingextremists,blacknationalists,whitesupremacists,Jewishextremists,environmentalists,andanti‐CastroCubanextremists.

GovernmentFacilitiesSectorTerroristattackstargetinggovernmentfacilitiesintheUnitedStatesalsotookplacenearlyeveryyearbetween1970and2015,with433attacksintotal.Theseattackscaused210deathsandmorethan780peopleinjured.Themajorityofthesedeaths(80%)andinjuries(83%)occurredasaresultofthe1995bombingoftheAlfredP.MurrahfederalbuildinginOklahomaCity.Anadditional7percentofdeathsand3percentofinjuriestookplacein2015whenassailantsinspiredbytheIslamicStateofIraqandtheLevant(ISIL)carriedoutanarmedassaultatalocalgovernmentfacilityinSanBernardino,California—thesecond‐deadliestattackagainstagovernmentfacilityduringthistimeperiod.Liketerroristattacksoncommercialfacilities,95percentofallattacksongovernmentfacilitieswerenon‐lethal.Themostfrequentlytargetedtypesofgovernmenttargetsweregeneralgovernmentbuildingsandoffices(42%),followedbydiplomatictargets(e.g.,embassiesandconsulates,diplomaticpersonnel,andinternationalorganizations;32%).Anadditional10percentofterroristattacksongovernmentfacilitiesimpactedtargetsassociatedwiththecourtssystem,(e.g.,courtbuildings,judges,andattorneys);6percenttargetedgovernmentpersonnel;and4percentwereaimedatpoliticiansandpoliticalpartytargets.Figure4showsthetypesofterroristattacksintheUnitedStatesthattargetedgovernmentfacilities.Comparedtoterroristattacksoncommercialfacilities,attacksongovernmentfacilitiesweresomewhatmorelikelytoinvolvebombings(62%comparedto55%),buthalfaslikelytoinvolvefacility/infrastructureattacks(20%comparedto40%).Attacksonthegovernmentfacilitiessectorwerealsomuchmorelikelytoinvolvetacticsfocusedparticularlyonpeople:armedassaults(7%),assassinations(6%),andunarmedassaults(includingtheuseofchemicalandbiologicalagents;3%).Barricadeincidentsandkidnappingseachcomprisedlessthan1percentofterroristattackstargetingthegovernmentfacilitiessector.



Figure4:TacticsofTerroristAttacksonGovernmentFacilitiesintheUnitedStates,1970‐2015(n=433)

For20percentoftheterroristattacksongovernmentfacilitiesintheUnitedStatesbetween1970and2015,noinformationabouttheperpetratorwasreportedinsourcematerials.Theremainingattackswerecarriedoutbyoperativesofmorethan80perpetratorgroupsandgenericdesignations,aswellasunaffiliatedindividualswithavarietyofideologicalinfluences.Theseperpetratorsofattacksongovernmentfacilitieswerediverse,perhapsevenmoresothantheperpetratorsofattacksoncommercialfacilities.Themostcommonperpetratordesignationidentifiedis“left‐wingmilitants,”whowereresponsiblefor14%oftheattacksongovernmentfacilities,allofwhichtookplaceintheearly1970s.Thesecondmostcommonperpetratordesignationis“Unaffiliatedindividual(s)”(11%)whichreferstoassailantswhowerenotknowntobeassociatedwithaformalorganizationbutwereactinginpursuitofoneormoreideologicalgoals.Thiscategoryincludesboththe1995bombinginOklahomaCityandthe2015assaultinSanBernardino.ThemostprolificformalorganizationresponsibleforterroristattacksongovernmentfacilitiesintheUnitedStateswastheJewishDefenseLeague(JDL).TheJDLwasactiveinthe1970sand1980s,andcarriedout6percentofallattacksagainstgovernmenttargets.

HealthcareandPublicHealthSectorThehealthcareandpublichealthsectorwastargetedin281terroristattacksbetween1970and2015;however,thepatternoftheseattacksovertimedifferedsignificantlyfromtheoveralltrend.Nearlythree‐quartersoftheattackstargetinghealthcareandpublichealthfacilities(73%)tookplacebetweenthemid‐1980sandmid‐1990s—specifically,1984to1997.Nearlyall(97%)oftheterroristattackstargetingthehealthcareandpublichealthsectorintheUnitedStateswerenon‐lethal.Combined,theseattacksresultedinatotalof12deathsand41peopleinjured.Unliketheothermostfrequentlytargetedcriticalinfrastructuresectors(commercialandgovernmentfacilities),attacksonhealthcarewerealmostexclusivelyfocusedonasingletypeoftarget—abortion‐

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Attack

ArmedAssault

Assassination UnarmedAssault

HostageTaking

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Number of Attacks

Type of AttackSource: Global Terrorism Database



relatedfacilitiesandpersonnel.Abortion‐relatedtargets—primarilyclinics—comprisedatleast95percentofallattacksonthehealthcareandpublichealthsectorintheUnitedStatesbetween1970and2015.Anadditional4percentoftheseattackstargetedclinicsandlaboratoriesmoregenerally.Accordingly,ofthecasesforwhichinformationaboutperpetratorswasreportedinsourcematerials(86%ofallattacksonthehealthcaresector),88percentwereattributedtogenericallyidentifiedanti‐abortionactivistsorindividualsunaffiliatedwithaparticularorganization,butnonethelessmotivatedbyanti‐abortionideology.Anti‐abortiongroupsincludingArmyofGod(8%),theChristianLiberationArmy(1%),andPhineasPriesthood(0.4%)werealsoidentifiedasperpetrators.Finally,oneattackin1970wasattributedtounspecifiedrevolutionaryleftists;oneattackin1971wasattributedtotheleftistgroupStudentsforaDemocraticSociety;oneattackin1979wasattributedtotheanti‐CastroCubangroupOmega‐7;andoneattackin2003wasattributedtotheAnimalLiberationFront(ALF).Figure5illustratestheweaponsusedinterroristattacksonthehealthcareandpublichealthsector.Nearlytwo‐thirds(72%)oftheattacksonhealthcaretargetsintheUnitedStatesbetween1970and2015involvedincendiaryweapons,includingarsonmaterials,gasoline,andalcohol.Anadditional20percentinvolvedexplosives,6percentinvolvedfirearms,andasmallnumberofattacks—2percentofthetotal—involvedotherweapontypessuchas“melee”weapons(e.g.,sharporbluntobjects),vehicles,andbiologicalweapons(specifically,anthrax).Figure5:WeaponsUsedinTerroristAttacksonHealthcareandPublicHealthintheUnitedStates,1970‐2015(n=281)

Other2%

Firearms6%

Explosives20%

Incendiary72%




Tenofthe12peoplekilledinterroristattacksagainsthealthcareandpublichealthtargetsintheUnitedStateswerekilledbyfirearms.ThisfigureincludesthedeadliestsingleterroristattackagainstahealthcarefacilityintheUnitedStates—the2015attackinwhichanassailantattackedaPlannedParenthoodfacilityinColoradoSprings,Colorado,killingthreepeople.Inaddition,itincludesthefirstdeathasaresultofabombingatanabortionclinic—asecurityguardkilledin1998—aswellasonepersonwhodiedasaresultofbecominginfectedwithinhalationanthraxin2001atahospitalinNewYorkCity.NotethatalthoughthislastincidenttookplaceinthecontextofaseriesofattacksinvolvinganthraxintheUnitedStatesinSeptemberandOctober2001,theexactcircumstancessurroundingthisparticularcaseareunclear.

FinancialServicesSectorThefinancialservicessectorintheUnitedStateswastargetedbyterrorists222timesbetween1970and2002;however,noterroristattacksonthissectortookplacebetween2003and2015.ThisdoesnotincludetheattacksinNewYorkCityonSeptember11,2001which,asstatedabove,wereclassifiedashavingtargetedtheTransportationSectordespitehavingimplicationsfornumerouscriticalinfrastructuresectors.Ofthese,221attackstargetedbanksorarmoredtrucks,andoneinvolvedanattemptedbombingataDieboldofficebuildinginSeattlein1977.Tenpeople,includingoneperpetrator,werekilledintheseattacks.

Table3:MostFrequentPerpetratorsofTerroristAttacksontheFinancialServicesSector,1970‐2002

Perpetrator Group Attacks Years Active

Fuerzas Armadas de Liberacion Nacional (FALN) 32 1974 ‐‐ 1982

Left‐Wing Militants 28 1970 ‐‐ 1972

Aryan Republican Army 16 1994 ‐‐ 1995

Black Liberation Army 12 1971 ‐‐ 1974

United Freedom Front (UFF) 11 1975 ‐‐ 1984

Weather Underground 10 1970 ‐‐ 1975

Macheteros 9 1981 ‐‐ 1998

May 19 Communist Order 8 1976 ‐‐ 1981

Chicano Liberation Front 8 1971 ‐‐ 1975

Independent Armed Revolutionary Commandos (CRIA) 5 1977 ‐‐ 1977

George Jackson Brigade 5 1976 ‐‐ 1977


Themajorityoftheterroristattacksthattargetedfinancialinstitutionswerebombings(61%),followedbyhostagetaking(barricade)events(19%),facility/infrastructureattacks(11%),andarmedassaults(9%).Table3showstheperpetratorgroupsandorganizationsthatwereresponsibleforthemostattacksthattargetedthefinancialservicessector.Manyofthebarricadeeventsandarmedassaultsinvolvedrobberiesofbanksandarmoredtruckscarriedoutbyorganizationsinpursuitofanideologicalgoal,includingtheAryanRepublicanArmy,theUnitedFreedomFront,andtheMay19CommunistOrder.Othergroupsreliedmoreheavilyuponbombings,includingthePuertoRicannationalistgroupFALN(FuerzasArmadasdeLiberacionNacional),theWeatherUnderground,theChicanoLiberationFront,andleft‐wingmilitantsnotknowntobeaffiliatedwithaparticularorganization.



DefenseIndustrialBaseSectorBetween1970and2015,190terroristattackstargetedthedefenseindustrialbasesectorintheUnitedStates,resultinginatotalof219deaths.Thedeadliestoftheseattackstookplacewhenal‐Qa’idatargetedDepartmentofDefenseheadquartersatthePentagoninArlington,Virginia,onSeptember11,2001,killingatotalof189peopleandinjuringmorethan100others.Thirteenpeoplewerekilledin2009whenMaj.NidalHasanopenedfireonsoldiersatFootHoodinKilleen,Texas.In2015,fivemilitarypersonnelwerekilledinoneoftwoarmedassaultscarriedoutinChattanooga,TennesseebyMohammadYoussufAbdulazeez,whowasultimatelyshotandkilledbyauthorities.TwoattacksinPuertoRicointhe1970seachkilledtwoNavypersonnel,andinsevenattacksondefensetargetsasinglevictimwaskilled.Sixoftheseattackstookplacebetween1970and1982,andoneoccurredatarecruitingfacilityinLittleRock,Arkansas,in2009.MorethanhalfofallattacksthattargetedthedefenseindustrialbasesectorintheUnitedStates(52%)tookplacein1970and1971,whenmanyperpetratorsweremotivatedbyoppositiontotheVietnamWar.Thenumberofattacksagainstmilitarytargetsdroppedfrom67in1970to32in1971to3in1972tozeroin1973.Duringthistimeperiod,perpetratorsoftheseattackswereidentifiedasleft‐wingmilitantsandstudentradicals.FewattackswerecarriedoutbyassailantsaffiliatedwithmoreformallyidentifiedorganizationssuchastheWeatherUnderground.Inthelate1970sand1980s,perpetratorsofattackstargetingthedefenseindustrialbasesectorweremorecommonlyPuertoRicannationalistorganizations,includingFALN,RevolutionaryCommandosofthePeople(CRP),LosMacheteros,andtheOrganizationofVolunteersforthePuertoRicanRevolution.From1978to2001,73percentofterroristattacksagainstdefenseindustrialbasetargets(51attacks)tookplaceinPuertoRico.Tenofthe15attacksinwhichperpetratorstargetedthedefenseindustrialbasesectorbetween2000and2015werecarriedoutbyindividualswhowerenotformallyaffiliatedwithterroristorganizations.ManyoftheseperpetratorsweremotivatedbyradicalIslamistideologyand—liketheanti‐warperpetratorsofterrorismtheearly1970s—wereopposedtoUnitedStatesmilitaryinterventioninIraqandAfghanistan,andinonecase,Kosovo.Themostcommontypesoftargetsamongterroristattacksagainstthedefenseindustrialbasesectorweremilitaryrecruitingstations(44%)andmilitarybasesorheadquarters(34%).Anadditional10percentofattacksondefensetargetswereagainstmilitarytransportationorpatrols.Figure6showsthevariationovertimeinweaponsusedinterroristattacksagainstthedefenseindustrialbasesector.Theprogressionfromtheuseofprimarilyexplosivesandincendiariesinthe1970s,1980s,1990s,and2000stotheuseoffirearmsinthefirstsixyearsofthe2010sgenerallyreflectsshiftingpatternsofweaponusageinterroristattacksagainstalltypesoftargetsintheUnitedStates.



Figure6:WeaponsUsedinTerroristAttacksonDefenseTargetsintheUnitedStates,bydecade(n=190)

EmergencyServicesSectorBetween1970and2014,157terroristattacksdirectlytargetedtheemergencyservicessector,killing57people.TheseattacksdonotincludetheattacksofSeptember11,2001,whichwereclassifiedashavingtargetedthetransportationsectorandthedefenseindustrialbasesector.Nor,doesitincludeotherattacksthathaveimpactedtheemergencyservicessectorduetoitsroleinsecurityandemergencyresponse.Followinganincreaseinattacksagainsttheemergencyservicessector,fromtwoattacksthatkilledtwopeoplein2013tosixattacksthatkilled10peoplein2014,therewerenoterroristattacksthatdirectlytargetedtheemergencyservicessectorin2015.Thevastmajorityofattacksontheemergencyservicessector(96%)targetedthepolice—includingbothpoliceofficersandpatrols(60%)andpolicebuildings(36%).Inaddition,threeattackstargetededucationalinstitutions(campuspolice);twoattackstargetedfirefighters;andtwoattackstargetedthepersonalpropertyofindividualsaffiliatedwithpolicing.Althoughthereisoftenoverlapinideologicalclassifications,theperpetratorsofattackstargetingtheemergencyservicessectorincludegroupsandorganizationsprimarilymotivatedbyextremeleft‐wingideology(74%),extremeright‐wingideology(3%),nationalist/separatistideology(14%),andsingle‐issues(2%),showninFigure7.Inaddition,7percentoftheseattackswerecarriedoutbyindividualsnotaffiliatedwithaparticularorganization.Theideologicalmotivationsoftheseunaffiliatedindividualsincludeanti‐government,anti‐police,andanti‐immigrationbeliefs,aswellasradicalIslamistideology.

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1970s (n=127) 1980s (n=39) 1990s (n=9) 2000s (n=8) 2010‐2015 (n=7)

Percent of Attacks

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Figure7:DominantIdeologyofPerpetratorsofTerroristAttacksTargetingtheEmergencyServicesSectorintheUnitedStates,1970‐2015(n=157attacks)

Theextremeleft‐wingorganizationsthattargetedtheemergencyservicessectorincludetheBlackLiberationArmy,theWeatherUnderground,andtheNewWorldLiberationFront,allofwhichwereactiveinthe1970s.Theextremeright‐wingorganizationsincludePosseComitatusandAryanNation,activeinthe1980s,agroupcalledOrganization544thatwasactiveinthe1990s,andperpetratorsthatself‐identifiedwiththeSovereignCitizenmovementinthe2010s.Thenationalist/separatistorganizationswereprimarilyPuertoRicangroupsactiveinthe1970sand1980s,includingFALN,LosMacheteros,andtheIndependentArmedRevolutionaryCommandos(CRIA).Singleissueorganizationsthatattackedtheemergencyservicessectorincludeananti‐CastrogroupcalledtheNationalIntegrationFront(FIN)andtheanti‐warPeople’sLiberationArmy(UnitedStates),bothactiveinthe1970s,aswellastheEarthLiberationFront(ELF),whichcarriedoutanattackinthe2000s.

EnergySectorTherewere109terroristattacksthattargetedtheenergysectorbetween1970and2014;noneoccurredin2015.Becausetheseattackswereprimarilyfocusedonpropertyandinfrastructure,theyresultedinzerofatalities.Two‐thirdsoftheattacksontheenergysector(70%)tookplaceinthe1970s;20percenttookplaceinthe1980s;5percenttookplaceinthe1990s;2percenttookplacebetween2000and2010;and3percenttookplacebetween2011and2015.Thetargetsofterroristattacksontheenergysectorincludedelectrical,gas,andoilinfrastructure,andinsomecasescorporateofficespacebelongingtoenergycompanies.Figure8illustratestheparticulartypesoftargets.Electricityinfrastructureandcorporationscomprised53percentofallattacksonenergytargets;6percenttargetedoilinfrastructureoroilcompanies;2percentoftheattackstargetedgasinfrastructureorgascompanies;andtheremaining39percenttargetedinfrastructureorcorporateoffice

74%

3%

14%

2%7%

Extreme Left‐Wing

Extreme Right‐Wing

Nationalist/Separatist

Single Issue

Unaffiliated Individual(s)

Note: 13% unknown perpetrator/ideologySources: Global Terrorism Database; Profiles of Perpetrators of Terrorism‐ US



spacethatwaseitherassociatedwithunspecifiedormixedusage(e.g.,propertybelongingtoPacificGasandElectric(PG&E)).Figure8:TypesofEnergyFacilities/InfrastructureTargetedbyTerroristAttacksintheUnitedStates,1970‐2015

(n=109)

Theseattacks—98percentofwhichwerebombings(85%)orfacility/infrastructureattacks(13%)—wereoftencarriedoutbyunidentifiedoffenders.Forone‐quarterofallattacksonenergytargets,noinformationabouttheidentityoftheperpetratorswasidentifiedinsourcematerials.Thisisconsistentwithattacksthataremorelikelytotargetpropertyandinfrastructure.Oftentheperpetratorswerenotatthesceneatthetimeoftheattack;insomecasestheyplantedanexplosiveorincendiarydeviceandleft.Amongtheattacksforwhichperpetratorswereidentified,morethanone‐third(34%)wereattributedtotheNewWorldLiberationFront(NWLF).TheNWLFwasanextremeleft‐wingorganizationthatcarriedoutmorethan20bombingstargetingtheenergysectorbetween1970and1978,primarilyaimedatelectricalinfrastructurebelongingtoPG&EinCalifornia.Theremainingattackswerecarriedoutbymorethan30differentgroupsororganizationsrepresentingavarietyofideologicalmotivations:extremeleft‐wing,extremeright‐wing,environmentalism,PuertoRicannationalism,andtheanti‐Castromovement.NearlyalloftheperpetratorgroupsidentifiedwereresponsibleforoneortwoattacksagainsttheenergysectorratherthanaprolongedpatternlikethatoftheNWLF.

TransportationSystemsSectorBetween1970and2015therewere89terroristattacksthattargetedthetransportationsystemssector,includingtheattacksonSeptember11,2001.Asnotedabove,althoughallfouroftheSeptember11thattackstargetedaircraft,theyimpactedanumberofothercriticalinfrastructuresectorsaswell.Threeoftheattacks—thoseinwhichplanescrashedinNewYorkandPennsylvania—havebeenclassifiedas

Electricity, 53%

Oil, 6%Gas, 2%

Other/Mixed, 39%




attacksagainstthetransportationsystemssector,whiletheonethattargetedthePentagoninVirginiawasclassifiedasanattackagainstthedefenseindustrialbasesector.Inadditiontothese,10otherattackstargetingthetransportationsystemssectorwerelethal.In1975perpetratorswhoweresuspectedtobeCroatiannationalistsdetonatedexplosivesataterminalatLaGuardiaAirportinNewYork,killing11peopleandwounding74others.TwoattacksatLosAngelesInternationalAirport(LAX)ticketcounterseachresultedinthreedeaths—oneinvolvinganexplosivedevicein1974andoneinvolvingashootingin2002.Sevenattackseachresultedinonedeath.ThetargetsoftheseincludedaCubanfishingvessel(1976),GrandCentralTerminalinNewYorkCity(1976),thePanAmericanAirlines(PanAm)terminalatJohnF.KennedyInternationalAirport(1981),aPanAmflightlandinginHonolulu,Hawaii(1982),anAmtraktraininArizona(1995),andmostrecentlytwoattackstargetingTransportationSecurityAgency(TSA)agentsin2013atLAXand2015inNewOrleans,Louisiana.Figure9:SuccessfulandUnsuccessfulAttacksthatTargetedTransportationSystemsintheUnitedStates,1970‐2015

(n=89)

Figure9showsthetypesoftacticsthatperpetratorsusedinattackstargetingtransportationsystemsintheUnitedStates,dividedintosuccessfulandunsuccessfulattacks.Notethatinordertoclassifythesuccessofattacksweevaluatetheextenttowhichtheintendedtactichappened,oncetheperpetratorwas“outthedoor”attemptingtoexecutetheattack.Thisdefinitionofsuccessisthereforenotareflectionofwhethertheattackersachievedtheirultimategoals,butinsteadisintrinsicallylinkedtothetypeofattack.Forexample,abombingwassuccessfulifthebombdetonated(evenifitdidnotachievetheintendedamountofdestruction),butunsuccessfulifitfailedtodetonateorwasdefusedharmlesslybyauthorities.Incontrast,ahijackingwassuccessfuliftheperpetratorssuccessfullygainedcontrolofthe

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vehicle,andanexampleofanunsuccessfulfacility/infrastructureattackisoneinwhichthearsonistattemptedtobutfailedtoigniteafire.Nearlytwo‐thirds(64%)oftheattacksontransportationtargetswerebombings,whichhadthelowestsuccessrateofalltacticsusedagainstthissector(77%successful).TheunsuccessfulbombingattemptwithperhapsthegreatestpotentiallethalityistheattemptbyUmarFaroukAbdulmutallabtodetonateexplosiveshewaswearingonNorthwestAirlinesFlight253upondescentintoDetroit,Michigan,in2009.AsimilarfailedattemptbyRichardReidtookplacein2001;however,thisparticularattackisnotincludedinthisanalysisbecauseittookplaceovertheAtlanticOcean.Hijackingscomprised15percentofallattacksontransportationtargetsandinvolvedaircraftinallcases.PriortotheSeptember11,2001attacksthemostrecentterroristhijackingintheUnitedStatestookplacein1984.Atotaloffourterrorism‐relatedaerialhijackingstookplaceintheUnitedStatesinthe1980s,andsixtookplaceinthe1970s,includingtwounsuccessfulattacksin1970and1971.Tenoftheattacksontransportationtargetswerefacility/infrastructureattacks,whichareintendedtocausepropertydamageratherthanlossoflife.Atleastfiveoftheseattacks,includingoneunsuccessfularsonattempt,werecarriedoutbyanimalrightsandenvironmentalistgroups.TheseperpetratorsincludedtheAnimalLiberationFront(ALF),theEarthLiberationFront(ELF),andagroupcallingitselfthePeople’sBrigadeforaHealthyGeneticFuture,whichsetfiretoahelicopterbeingusedtosprayherbicidesonforestsinOregon.Finally,ninearmedassaultstargetedpeopleandpropertyassociatedwiththetransportationsystemssector.Allnineoftheseattacksweresuccessfulassaults,meaningthattherewereeitherhumancasualtiesorpropertydamagecaused.Sixinvolvedfirearmsorknives,andthreeinvolvedincendiarydevicesofsomekind.Specifictargetsoftheseattacksincludedmaritimevessels,helicopters,airportsandairlinepersonnel/property,andtheNewYorkCitySubwaysystem.

FoodandAgricultureSectorTherewere54attackstargetingthefoodandagriculturesectorbetween1970and2015,threeofwhichwerelethalandresultedinatotalofsevendeaths.Thisincludestwoattacksin1975inwhichFALNoperativesdetonatedexplosivesatarestaurantinNewYorkCity,killingfourpeopleandwoundingmorethan50,andunidentifiedperpetratorsdetonatedexplosivesatarestaurantinSanJuan,PuertoRico,killingtwopeopleandwounding11others.Thethirdattack—carriedoutin1982andreportedlyclaimedbytheJewishDefenseLeague—wasanarsonataLebaneserestaurantinNewYorkCity,whichkilledonepersonandwoundedeightothers.Althoughnon‐lethal,twoattacksin1984inwhichmembersoftheRajneesheereligiouscultcontaminatedsaladbarsinrestaurantswithsalmonella,mademorethan750peopleill.Thegoaloftheseattackswastoinfluencelocalelections.Morethanthree‐quartersofallterroristattacksonfoodandagricultureintheUnitedStates(76%)targetedrestaurants,bars,cafes,orotherretailspaces.Anadditional16percenttargetedindustrialinfrastructure,includingfactories,and8percentspecificallytargetedfarmsorranches.Also,mostofthe



terroristattacksonfoodandagriculture(54%)involvedincendiarydevicesorarson.Arsonattacksonfoodandagriculturetargetsweretypicallycarriedoutbyanimalrightsandenvironmentalistgroups,includingALF,ELF,andagroupthatcalleditselftheFarmAnimalRevengeMilitia(FARM).Approximatelyone‐thirdofattacksonfoodandagricultureinvolvedexplosivedevices.Theseattackstookplaceinthe1970sand1980s,withtheexceptionofthreeattacksthattookplaceinthe1990s.Theperpetratorgroupsthatmostfrequentlyusedexplosivedevicesweretheextremeleft‐wingNWLF,thePuertoRicannationalistgroupFALN,andwhitesupremacistsincludingmembersofAryanNation.Threeattacks(6%)targetedfoodandagricultureusingfirearms.TheseincludetworobberiesthatwerecarriedoutbytheBlackLiberationArmyandtheMay19CommunistOrder,andanadditionalattackcarriedoutbythePuertoRicannationalistgroupcalledArmedForcesofPopularResistance(FARP).TheonlyterroristattacksonfoodandagriculturethatinvolvedbiologicalweaponswerethoseconductedbyRajneesheesin1984,describedabove.Andfinally,oneattacktookplaceinwhichunidentifiedperpetratorsusedchemicalweapons—twoacidbombsdetonatedatpopularrestaurantsinFloridain2010.

OtherSectorsFewerthan25terroristattacksbetween1970and2015targetedeachoftheremainingsectors,includingthecriticalmanufacturingsector,thecommunicationssector,thechemicalsector,thewaterandwastewatersystemssector,theinformationtechnologysector,thenuclearreactors,materials,andwastesector,andthedamssector.Combined,attackstargetingthesesectorsresultedintwodeathsand11peopleinjured.Infact,oneofthe66attacksagainstthesesectorswaslethal,a1978arsonattackonacommunicationsfacilityinSanJuan,PuertoRico.

ConclusionsThisanalysisofterrorismtargetingcriticalinfrastructureintheUnitedStatesbetween1970and2015revealsavarietyofpatternsandtrends.Thepurposeofthisanalysisistodemonstratewhattypesofinformationareavailableandprovideageneraloverviewofpatternsofterroristattacksagainstcriticalinfrastructuresectorswithrespecttopatternsovertime,targets,tactics,weapons,lethality,andperpetrators,generatingadditionalresearchthemesforfutureanalysis.Possibleavenuesforfutureresearchmayinclude:1)in‐depthanalysisofparticularattacksortactics,2)assessmentofattacksthatimpactmultiplecriticalinfrastructuresectors,3)greaterfocusonsectorsthathavebeentargetedmorerecently,giventhatthosewithgreaterhistoricalsignificancemaynotaccuratelyreflectcurrenttactics/threats;4)analysisofattacksoncriticalinfrastructurewithparticularfocusongeographiclocation;5)considerationofmajorrecentattacksthathavetargetedcriticalinfrastructureoutsidetheUnitedStatesandpotentialimplicationsforcriticalinfrastructureintheUnitedStates;6)investigationoftheextenttowhichattacksoncriticalinfrastructureresultinpropertydamage;and7)additionalperpetrator‐focusedresearchwithrespecttotargetingcriticalinfrastructure,includingdevelopmentoftacticalprofilesofperpetratorgroupsaswellasgreaterfocusontheroleofunaffiliatedindividuals.