▁throughout ▁the ▁city , ▁and ▁identify ▁whom ▁they ▁have ▁been ▁with ▁– ▁has ▁been ▁argued ▁by ▁some ▁to ▁present ▁a ▁risk ▁to ▁civil ▁libert ies . ▁T rap wire ▁is ▁an ▁example ▁of ▁such ▁a ▁network . ▁ ▁Social ▁network ▁analysis ▁ ▁One ▁common ▁form ▁of ▁surve ill ance ▁is ▁to ▁create ▁maps ▁of ▁social ▁networks ▁based ▁on ▁data ▁from ▁social ▁networking ▁sites ▁such ▁as ▁Facebook , ▁My Space , ▁Twitter ▁as ▁well ▁as ▁from ▁traffic ▁analysis ▁information ▁from ▁phone ▁call ▁records ▁such ▁as ▁those ▁in ▁the ▁NS A ▁call ▁database , ▁and ▁others . ▁These ▁social ▁network ▁" maps " ▁are ▁then ▁data ▁m ined ▁to ▁extract ▁useful ▁information ▁such ▁as ▁personal ▁interests , ▁friend ships ▁& ▁affili ations , ▁wants , ▁belief s , ▁thoughts , ▁and ▁activities . ▁ ▁Many ▁U . S . ▁government ▁ag encies ▁such ▁as ▁the ▁Def ense ▁Advanced ▁Research ▁Project s ▁Agency ▁( D AR PA ), ▁the ▁National ▁Security ▁Agency ▁( NS A ), ▁and ▁the ▁Department ▁of ▁Hom eland ▁Security ▁( D HS ) ▁are ▁invest ing ▁heavily ▁in ▁research ▁involving ▁social ▁network ▁analysis . ▁The ▁intelligence ▁community ▁bel ieves ▁that ▁the ▁biggest ▁threat ▁to ▁U . S . ▁power ▁comes ▁from ▁decent ral ized , ▁leader less , ▁ge ograph ically ▁dispers ed ▁groups ▁of ▁terror ists , ▁sub vers ives , ▁extrem ists , ▁and ▁diss idents . ▁These ▁types ▁of ▁thre ats ▁are ▁most ▁easily ▁counter ed ▁by ▁finding ▁important ▁nodes ▁in ▁the ▁network , ▁and ▁removing ▁them . ▁To