( CNN ) -- Violence has flared again in northwest Pakistan , where terrorists attacked army troops and two militant groups announced an alliance intent on starting a war against security forces . Pakistani army spokesman Asim Bajwa said in a statement Saturday that close to 60 terrorists struck security forces in Khyber Agency , a region west of Peshawar that borders Afghanistan . The two sides waged a lengthy battle , after which 17 militants were dead while others managed to escape , Bajwa said . The Pakistani Taliban claimed responsibility for the attack . The region has long been a hotbed for armed anti-government activity , not to mention U.S. drone strikes targeting suspected terrorists . Sources : Drone strikes kill 8 in Afghanistan , Pakistan . The Pakistani Taliban has been one of the most destabilizing forces in the Asian nation . In a statement , the outlawed organization threatened to foment more unrest as it announced it will send fighters to Khyber Agency and join forces with the militant group Lashkar-i-Islam . There , the allied forces plan to wage war with Pakistani authorities , according to the statement .
NEW : Pakistani Taliban takes credit for attack . Pakistani army spokesman : Militants strike government troops in northwest Afghanistan . two suspected militants died , others escape after long battle , spokesman says . Lashkar-i-Islam says it 's joining forces with fellow militant group Pakistani Taliban .