WASHINGTON ( CNN ) -- The FBI and the Department of Homeland Security issued a bulletin Thursday citing an alleged claim of responsibility by al Qaeda for former Pakistani Prime Minister Benazir Bhutto 's assassination , a DHS official told CNN . An Italian news agency says al Qaeda No . 2 Ayman al-Zawahiri began planning Bhutto 's killing in October . But such a claim has not appeared on radical Islamist Web sites that regularly post such messages from al Qaeda and other militant groups . The source of the claim was apparently Italian news agency , Adnkronos International ( AKI ) , which said that al Qaeda Afghanistan commander and spokesman Mustafa Abu Al-Yazid had telephoned the agency to make the claim . `` We terminated the most precious American asset which vowed to defeat [ the ] mujahadeen , '' AKI quoted Al-Yazid as saying . According to AKI , al Qaeda No . 2 Ayman al-Zawahiri set the wheels in motion for the assassination in October . One Islamist Web site repeated the claim , but that Web site is not considered a reliable source for Islamist messages by experts in the field . The DHS official said the claim was `` an unconfirmed open source claim of responsibility '' and the bulletin was sent out at about 6 p.m. to state and local law enforcement agencies . The official characterized the bulletin as `` information sharing . '' Ross Feinstein , spokesman for Director of National Intelligence Mike McConnell , said the U.S. intelligence community is monitoring the situation and trying to figure out who is responsible for the assassination . `` We are not in a position to confirm who may be responsible , '' Feinstein said . Feinstein said that the intelligence community `` obviously analyze ( s ) open source intelligence , '' but he would not say whether the community believes the claim has any validity . For now , he said , there is `` no conclusion '' as to who may be responsible . Earlier , DHS spokesman Russ Knocke said Bhutto 's assassination had not prompted `` any adjustments to our security posture . '' `` Of course , we continue to closely monitor events as they unfold overseas , '' he said . E-mail to a friend . CNN 's Jeanne Meserve contributed to this report .
FBI , Department of Homeland Security issue bulletin Thursday . Bulletin says two al Qaeda associates made claim to news agency . `` We terminated the most precious American asset , '' associate says . DHS official says the claim has not been confirmed .