The fear of terrorism has penetrated nearly every corner of American life, with even the fantasy realm of Walt Disney World taking new steps to address the harsh reality of possible violent attacks.
As retaliation for last month's terrorist attacks began Sunday with thundering explosions in Afghanistan, a domestic security clampdown took hold across the country.
FBI officials said there were no specific threats, but urged all local law enforcement agencies to move to their highest level of alert, and ``be prepared to respond to any act of terrorism or violence.''
Many cities _ Atlanta, Houston and San Francisco among them _ said security was already high before Sunday's military strikes. ``It's kind of hard to go to too much of a higher level,'' said Lucien Canton, director of San Francisco's Office of Emergency Services.
Walt Disney World, near Orlando, Fla., was one of several public places that has been scrambling to deal with the threat of terrorism. Disney World spokeswoman Marilyn Waters said the theme park is taking several steps to increase security.
``Those were both in reaction to the Sept. 11 attacks and also in anticipation of any retaliation,'' she said.
Few areas of the nation's public life went untouched. State troopers were posted at an NFL football game in Maryland. Bomb-sniffing dogs checked bags at New York's Pennsylvania Station. And Missouri's state Capitol was closed to visitors.
Even the Emmy Awards show was called off, though not because of security concerns, organizers said. They said holding the ceremony would have been inappropriate under the circumstances.
For many, the new security steps were envisioned weeks ago.
In New Jersey, authorities said they had planned to increase security following any U.S. retaliation, said state police Superintendent Carson Dunbar. He would not provide specifics, but said it involved state and local law enforcement, local emergency management centers, the National Guard and the Corrections Department.
In Baltimore, Police Commissioner Edward Norris said higher security went into effect at critical areas such as water plants, gas lines and communication networks.
``We knew the strikes were coming,'' Norris said.
The State Department on Sunday issued a worldwide caution to Americans, warning of the possibility of ``strong anti-American sentiment and retaliatory actions against U.S. citizens and interests throughout the world.''
In Detroit, Metro Airport spokeswoman Barbara Hogan said the Federal Aviation Administration notified officials at 2 p.m. to put additional security in place. It all will be ``behind the scenes'' and not noticed by passengers, she said.
Several airport representatives in Florida said they were increasing the number of visible, armed personnel at the request of the FAA.
An FAA spokesman, however, said no security changes at airports had been requested on Sunday.
``The airports and the air carriers know exactly what to do in this event,'' said FAA spokesman Chris White in Atlanta.
At Kansas City International Airport, officials doubled the number of police officers and other security, spokeswoman Erica Hupp said. As authorities have done since last month, each vehicle entering parking garages has been searched, she said.
Passengers at Atlanta's Hartsfield Airport, the nation's busiest, looked up from ticket lines Sunday and applauded as National Guardsmen marched in.
In New York, Mayor Rudolph Giuliani said more armed police officers and Guardsmen were put in place at security checkpoints on Sunday, but added that no bridges, tunnels or public places would be closed without a specific threat.
As a safety precaution, police closed a street next to New York's Grand Central Terminal. Police also shut down the street in front of the State Department in Washington.