Across the Washington area, the outbreak of war in Iraq prompted further tightening of the security already in place to guard against terrorism, and District leaders pronounced the capital safe as they urged people not to cancel their plans to visit the city.

The Washington field office of the FBI assembled a list of about 400 local Iraqis and began interviewing them, seeking information that would assist U.S. forces in the Persian Gulf or the investigation of terrorist activity in this country. Van Harp, head of the field office, said the interviews were being conducted "to ensure that we leave no stone unturned and try and obtain all information and intelligence to prevent another terrorist incident."

On other fronts, D.C. police pumped up neighborhood patrols, Metro transit officers conducted extra sweeps of stations to look for explosives, and some area governments began checking the identification of everyone entering public buildings. The Metro system also restricted bus service near military bases.

As far away as Prince William County, police activated an emergency plan to boost staffing and increase surveillance at major bridges and public gathering spots such as the Potomac Mills mall. Howard County activated its emergency operations center Wednesday night and ordered all police and fire department personnel to be ready to report to duty within one hour.

In all cases, law enforcement officials said they were not reacting to any specific information but taking extra precautions to address the general terror threat and to reassure the public.

D.C. Police Chief Charles H. Ramsey said at a news conference that he was "comfortable with the plans we have in place" and declared the capital safe for residents, workers and visitors.

"I think Washington is probably the safest place to be," Ramsey said. Asked what his message was to the public, he said: "Come on down to enjoy yourselves. There's no reason for people to cancel their plans. If we knew something like [an attack] would occur, we'd alert people, but right now there's no indication of that."

Ramsey, who was joined at the news conference by Deputy Mayor for Public Safety Margret Nedelkoff Kellems, vowed not to let antiwar demonstrators disrupt traffic.

They made their comments two days before the start of the National Cherry Blossom Festival, an event that kicks off the city's spring tourism season.

The FBI had planned to start interviewing Iraqi residents as soon as the war began. The bureau said the interviews will be voluntary and low-key and that in addition to soliciting information, agents will encourage Iraqis to report any hate crimes against their community. The vast majority of the estimated 5,000 Iraqi immigrants in the area are staunchly opposed to the regime of Saddam Hussein.

Law enforcement sources said the FBI is particularly interested in talking to people with ties to the Iraqi army or knowledge about terrorist organizations. They said that many of the Iraqis to be interviewed by the Washington field office live in Northern Virginia and that the Baltimore FBI office plans to talk to about 60 Iraqis in its region, including many from Prince George's and Montgomery counties.

In other war-related security measures, Maryland authorities posted officers at entrances to the Port of Baltimore; the Calvert Cliffs nuclear power plant cut off public tours; and the Maryland Transportation Authority Police opened a mandatory inspection station on northbound Interstate 95 for trucks over five tons.

Officials in several jurisdictions asked members of the the public to be more attentive when going about their routines and to report suspicious activity. First Sgt. Kim Chinn said Prince William police were receiving a larger-than-usual volume of calls yesterday.

Anne Arundel County Executive Janet S. Owens (D), whose county partially activated its emergency operations center yesterday, said, "Do not underestimate the importance of keeping your eyes and ears open."

Officials also began looking at the fiscal impact of the additional security they have put into place because of the war and the Code Orange terror alert level. Homeland Security Director Tom Ridge told state officials Wednesday that the Bush administration will request funds to offset their expenses. No estimates of those costs were available yet, but Ramsey provided some salary data suggesting that the District's costs alone would run into hundreds of thousands of dollars a day.

Maryland, Virginia and the District also are following Ridge's directive to deploy more officers to protect a half-dozen or so "critical assets" within their jurisdictions -- sites such as military bases, trucking or shipping ports and chemical stockpiles.

At the Joint Operations Command Center at police headquarters in the District, members of local and federal law enforcement agencies monitor news footage and the feeds from cameras trained on various Washington sites.