But many law enforcement agencies say they have been at their highest states of alert for weeks and aren't sure what more they can do.
Although some lawmakers supported the administration's decision to issue a broad warning, others complained that the alert was too vague to help protect people from terrorists.
The FBI notified about 18,000 law enforcement agencies nationwide Monday that it had received "credible" information that there could be more terrorist attacks in the next week. In Los Angeles, the LAPD went on a citywide tactical alert Monday night in the hours after the warning was issued, but then changed that to a modified alert Tuesday. The downgrade meant officers would resume responding to nonemergency calls.