Washington ( CNN ) -- In the wake of the suicide bombing at Forward Operating Base Chapman , new security guidance has gone out to U.S. bases across Afghanistan , U.S. military officials said . The December 30 suicide attack killed seven CIA officers and contractors , along with a Jordanian military officer who was the attacker 's handler . Former CIA official Robert Richer called it the greatest loss of life for the agency since the 1983 bombing of the U.S. Embassy in Beirut , Lebanon , which killed eight agents . A U.S. intelligence official , speaking on condition of anonymity , told CNN on Wednesday the attack was believed to have come on orders from `` the highest levels '' of al Qaeda . Bruce Reidel , a former CIA officer who has advised President Obama on al Qaeda , said the attack showed the capacity of terrorists to strike at U.S. targets remained `` very significant . '' `` It 's a very , very sophisticated operation , '' Reidel said . `` It must have taken a long time to plan and to set up . '' In response , U.S. military officials said they were changing procedures . `` Suffice it to say that after any serious incident we evaluate the circumstances , think through the threat implications given our current practices and disseminate guidance to the field if adjustments are necessary , '' a senior military official said . The official would not describe the new security procedures because `` we do n't broadcast the specific changes we 've made to security postures or our intelligence procedures . '' A second U.S. military official said the guidance is meant to adjust procedures as quickly as possible on a large scale . `` We do n't want just the military intelligence guys looking out for specific things . We need MPs and ground forces to be aware , '' the official said . The official said the security guidance is meant to be disseminated to as wide a group as possible , while more specific guidance on intelligence operations is kept to a much more limited , restricted distribution . The officials had not seen specific guidance on handling sources , but both noted only one week has passed since the incident , and the investigation may not have progressed far enough to produce formal recommendations in that area . One official said the intelligence officers on the ground now know enough details to `` self-correct '' procedures . According to sources , the Jordanian suicide bomber was Humam Khalil Abu-Mulal al-Balawi , a one-time militant who then appeared to be helping the United States . Al-Balawi was offering information on the possible whereabouts of Ayman al Zawahiri , the deputy to Osama bin Laden , the sources said , and was picked up outside the base and driven into it without being checked . The sources said al-Balawi detonated the bomb shortly after arriving . The attack shed light on the role of Jordan as a previously covert partner in the U.S. hunt for bin Laden and Zawahiri . `` The Jordanian intelligence service is the best intelligence service in the Middle East and South Asia , bar none , '' Reidel said . `` They are far more effective in working against jihadist groups like al Qaeda in Iraq like the al Qaeda core in Pakistan than any other intelligence service . '' CNN 's Barbara Starr and Pam Benson contributed to this report .
Senior official : `` After any serious incident we evaluate the circumstances '' New security guidance has gone out to U.S. bases across Afghanistan , official says . Intelligence official : `` We have a new policy that will be implemented in coming days and weeks. Guidance meant to adjust procedures quickly on a large scale , official says .