WASHINGTON -- Concerned about more terrorist attacks, the FBI on Sunday urged law enforcement agencies nationwide to move to their highest level of alert after the U.S. military strikes in Afghanistan.
"All law enforcement agencies have been asked to evaluate whether additional local security measures are warranted in light of the military operations and the current threat level," the FBI said.
The bureau issued the advisory through its National Threat Warning System after U.S. jets and missiles targeted Afghan military sites and camps belonging to Osama bin Laden.
Local law enforcement departments were asked to "be at the highest level of vigilance and be prepared to respond to any act of terrorism or violence should it become necessary."
FBI officials said they had no specific threats, but U.S. intelligence and Attorney General John Ashcroft had been warning for days there was a high likelihood of additional terrorism activity, particularly after the U.S. took its first military action.
Increased security was evident nationwide.
The Coast Guard expanded armed defense of major ports Sunday and added special security zones around sensitive piers, waterways and other facilities in the agency's largest port defense operation since World War II.
Within hours of the first strikes by American and British warplanes, Missouri shut the doors at its state Capitol to visitors, Utah state troopers were shifted from their desks to the highways and airport officials in Chicago, Detroit, Kansas City and Florida further tightened security.
The Energy Department placed its facilities, including nuclear weapons laboratories and nuclear materials storage areas, on a heightened level of security, spokeswoman Jeanne Lopato said.
District of Columbia police closed off a main street in front of the State Department as a precaution. The department warned of the possibility of "strong anti-American sentiment and retaliatory actions against U.S. citizens and interests throughout the world." It urged Americans overseas to monitor local news, limit their movements and stay in touch with U.S. embassies and consulates.
President Bush remained at the White House, working from the Oval Office and the first family's residential quarters. Vice President Dick Cheney was taken elsewhere, presumably so the two leaders would not be in the same place should disaster strike, but the White House would not say where.
"The current operating instructions are based on the possibility of additional terrorist activity occurring somewhere in the world," the FBI said.
In a sign of the heightened suspicions, in suburban Maryland two rental trucks carrying staging equipment used at a tribute to fallen firefighters - a tribute attended by Bush earier in the day - was stopped by state police and inspected by bomb sniffing dogs.
Airport traffic was running normally, said Marcia Adams, speaking for the Federal Aviation Administration. She said the FAA did not send out any new directives to airlines or airports.
The Coast Guard ordered 24-hour armed surveillance at more than 300 U.S. ports, covering every major point of entry, spokesman Cmdr. Jim McPherson said.
The agency increased from 51 to 72 the number of special security zones surrounding such facilities as nuclear power plants and piers where oil is loaded and unloaded, McPherson said.
Together, the changes added up to the largest Coast Guard mobilization to defend U.S. ports in more than 50 years, McPherson said.
"A lot of this is because of the USS Cole incident," McPherson said, referring to the suicide attack on a Navy ship moored in Yemen last year that killed 17 sailors and injuring 37.
The changes followed an increase Thursday in the amount of notice that all ships must give to enter U.S. ports, McPherson said. Instead of 24 hours, ship captains must provide 96-hour notice, and the Coast Guard then checks crew, passenger and cargo manifests. McPherson would not say if the change was in preparation for Sunday's military strikes.
Since the Sept. 11 terrorist attacks in New York and Washington, the Coast Guard has also maintained separate naval protection zones around Navy and Coast Guard ships, a procedure that had not been used since World War II, McPherson said.
The zones mean that both U.S. and foreign ship captains must notify the Coast Guard if they will pass within 500 yards of a Navy or Coast Guard ship. If a violator closes to within 100 yards the ship may defend itself or the intruding vessel may be seized. The violator faces up to six years in federal prison and a $250,000 fine, McPherson said.
Seeking to assuage Americans' fears, Bush planned to swear in former Pennsylvania Gov. Tom Ridge as head of the new Office of Homeland Security on Monday. Ridge will lead an office of 12 new employees in a West Wing space near the Oval Office, and will coordinate with some 100 administration staff members, White House spokesman Scott McClellan said.