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 .
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 : Attack believed to come from `` the highest levels '' of al Qaeda . Guidance meant to adjust procedures quickly on a large scale , official says .