WASHINGTON -- Security was tightened yesterday at U.S. airports, power plants, ports and other key installations as the nation braced for possible terrorist attacks by agents of Iraq, long a sponsor of international terrorism.
In response to Iraqi threats that a U.S. attack would provoke terrorist retaliation against Americans, the White House and Congress bolstered their security forces with dozens of extra police officers.
A chest-high fence was erected around the Capitol grounds, allowing normal access now but with passageways in the fence that could be closed quickly to prevent an attack.
Even members of Congress, usually recognized by the police, were asked for identification as they drove into underground garages.
The sidewalk in front of the White House was closed and a fence put up along Pennsylvania Avenue, keeping anti-war protesters from moving toward the presidential grounds.
"You will see increased inspections and other kinds of measures as we go through the weeks ahead," said presidential spokesman Marlin Fitzwater.
Patrols were also augmented around the capital's national monuments, which are routinely considered terrorist targets. The Pentagon has canceled all unscheduled building tours, and the State Department announced that it was stepping up its inspection of vehicles and deliveries.
The United States has long been immune to the kind of terrorist attacks that have plagued Europe for two decades. And administration officials believe that, should Iraq carry out its threat, terrorism most likely would be directed at Americans abroad.
But yesterday's precautions underscored concern that Iraqi agents may easily be able to penetrate the long and wide-open borders of the United States and launch attacks in this country.
The most likely targets, according to government and anti-terrorist experts, are New York and Washington.
"For the first time, the United States is a serious target for terrorism," Vincent Cannistraro, former chief of counterterrorism operations at the CIA, said in an interview with CBS.
Iraq already has a rudimentary network of terrorists in the United States, he said. Last year, the State Department expelled an Iraqi intelligence officer at Iraq's U.N. mission who was suspected of involvement in the killing of an Iraqi dissident in the United States.
The State Department issued a statement saying the government "has evidence that terrorists supported by Iraq are planning to mount attacks in most regions of the world."
"We believe the Middle East and Europe are the most likely locations," the statement said. "We also have reports of terrorist planning in Africa, Asia and Latin America."
The department also said that, should war erupt in the Persian Gulf, "the threat of terrorism against American citizens would increase significantly."
As a precautionary measure, the Immigration and Naturalization Service has begun photographing and fingerprinting travelers to this country carrying Iraqi and Kuwaiti passports.
In addition, the State Department ordered all but four Iraqi diplomats to leave the United States by yesterday to preclude their "orchestrating" terrorist attacks.
FBI agents are monitoring known members of radical Palestinian, Libyan and other groups that could launch terrorist acts.
Prominent Arab-Americans also have been interviewed by the FBI about potential terrorism. Many have vehemently protested, saying the meetings impugn Arab-Americans' loyalty to the United States.
Following are among additional anti-terrorist measures that have been taken as the prospect of war has increased:
* The Nuclear Regulatory Commission has ordered nuclear plant operators to step up their precautions.
* Police patrols in many state capitols have been intensified and guard forces at governors' residences also have been enlarged. Florida took special measures because it is a tourist center and host to the Super Bowl later this month.
* Leading U.S. corporations, including the Big Three automakers, have announced they are tightening security at factories worldwide.
* International travel for employees of many U.S. companies has been curtailed, especially to the Middle East.
* The Coast Guard has moved to protect U.S. ports and coastal factories, and airports have enhanced the security screening of passengers.
The last international terrorist attack in the United States was carried out by Japanese radicals in Miami in 1983, according to the Associated Press.