Fears of Possible Terror Attack Build

Americans and law enforcement nationwide braced themselves today for a possibly imminent terrorist attack, with officials focusing on the nation's previous targets — Washington, D.C., and New York.

Tension was high in both New York and Washington as officials prepared for an attack either today or Friday — which coincided with war tension with Iraq and the end of the hajj, a Muslim holy period.

Police around the country stepped up patrols and heightened security measures officers carrying semiautomatic rifles patrolled the U.S. Capitol building and the government warned key industries and utilities to be on alert for employees that may have been planted by al Qaeda and other terrorist organizations.

Despite the warning, Justice Department officials said today that they did not plan to raise the five-stage threat level to red, which would signal an imminent or ongoing attack. The level is currently orange, or high risk of attack.

In Washington, Black Hawk helicopters patrolled the skies, ready to call in F-16 fighter jets if any planes try to violate restricted airspace. On the ground, the military deployed heat-seeking Stinger missiles with a range of up to two miles, to be used if suspicious planes refuse to respond to orders to leave the area.

Hospital officials in New York were warned to be prepared to deal with a possible cyanide attack. The government urged them to build up stocks of sodium thiosulfate, the antidote to cyanide poisoning, as well as treatments for biological and chemical warfare. Doctors were also warned to be on the lookout for clusters of patients with respiratory, neurological or skin conditions.

New York police, armed with radiation detectors and gas masks, were out in force in the subways, at train stations and airports and at the bridge and tunnel crossings into the city.

At a news conference this afternoon, Mayor Michael Bloomberg said 16,000 law enforcement officials trained to combat terrorism were deployed throughout the city. Air patrols have also returned to New York.

"We are constantly changing what we're doing so no one can predict what instruments we'll be using and where we'll be going," Bloomberg said.

The mayor stressed that while people should be vigilant, they should also be aware that New York City has been on code level orange for 17 months — since the Sept. 11, 2001, attacks that destroyed the World Trade Center.

"We have been at code level orange for 17 months, and for 17 months we have not had a terrorist attack," Bloomberg said.

New Yorkers, and people around the country, should not be frozen by fear and must carry on with their daily lives, the mayor said. New York Gov. George Pataki said it is important for people to be alert to anything suspicious around them, but that they should not spread rumors that could create panic.

"We are in a war and there are people who want to kill us, but we're meeting that challenge," said James Kallstrom, the head of the Counterterrorism Task Force for New York. "But people need to carry on. Be a little content with the notion that we've got a great team. We know what we're doing."

Warning to Key Industries

The FBI and National Infrastructure Protection Center issued an alert to critical industries and key facilities that they should take steps to guard against potential terrorist attacks.

The bulletin advised checking for possible infiltrators among employees, varying security routines and checking Internet sites that describe their facilities to "consider how that information might assist terrorists interested in planning an attack. Operatives will likely research potential targets extensively prior to an attack."

The apparently increasing threat of new terrorism has Americans on edge. Hardware stores have reported runs on flashlights and batteries, as well as duct tape and sheets of plastic, which the Department of Homeland Security has recommended for people to use to create secure rooms in their homes.

And it's not just in New York and Washington that people are worried.

"We have some extra food and water put back. An ounce of prevention can go a long way," said Jon McCormick of Indiana. "There is a grim mood from everyone about the possibility of attack, but everyone seems to be prepared to ride it out."

Threats Overseas, Too

American officials said the threat overseas may be just as great, particularly in the Arab countries cited in an audiotape from Osama bin Laden that aired on Arab television on Tuesday.

Among the prime targets, officials told ABCNEWS, could be Saudi Arabia's Ras Tanura oil refinery — the largest in the world. Police in London were putting on a show of force at Heathrow airport that rivals anything seen in the United States.

At Gatwick Airport, outside London, the North Terminal was closed today after police discovered a live grenade in the luggage of a passenger. The man, who police said was from Venezuela, was arrested and charged under the Prevention of Terrorism Act.

The State Department today issued travel warnings for Bahrain and Qatar, and upgraded the warning for Saudi Arabia that was issued on Jan. 30. The warnings authorize the voluntary departure of all non-emergency personnel and family members from the U.S. embassies, and urge private American citizens to rigorously evaluate their own security situations.

‘Packages of Importance’

The heightened alert comes less than one week after the Department of Homeland Security announced that the nation's five-step alert system had been raised to "high," the first time the level had been increased since the anniversary of the Sept. 11, 2001, attacks.

Perhaps more significantly, though, it comes after U.S. intelligence intercepted suspected terrorist communications talking of "the underground" and "packages of importance."

The intercepted communication refers to the hajj and indicates plots with radioactive materials or chemical agents, law enforcement officials said.

"If given the choice, al Qaeda terrorists will choose attacks that achieve multiple objectives, striking prominent landmarks, inflicting mass casualties, causing economic disruption and rallying support through shows of strength," CIA Director George Tenet told the Senate Armed Services Committee.

While the preparations were made to mitigate the effects of any possible attack, authorities hope that the show of force will rob terrorists of the element of surprise, and possibly forestall terrorists from following through on any plans.

New Bin Laden Tape?

Meanwhile, Washington officials were examining yet another audiotape that may be from bin Laden — the second tape from the al Qaeda leader to surface this week.

A British-based Islamic news agency says it has a new bin Laden recording, an alleged 53-minute last will and testament. A voice purported to be that of the terror mastermind predicts he will die "a martyr" this year in an attack against his enemies. Al-Ansaar news agency said today it bought the tape over the weekend after discussions with an anonymous Internet seller.

U.S. counterterrorism officials are reviewing a transcript of the tape, but so far they have not been able to confirm that it's an authentic message from the terror chief.

At the same time, the U.S. government is aggressively pursuing intelligence that Iraqi President Saddam Hussein may have sent operatives to the United States, ABCNEWS has learned.

Sources told ABCNEWS that the possibility of Iraqi infiltrators is one reason why the FBI has launched a massive campaign to interview 50,000 Iraqi-Americans and Iraqis living in the United States. Of particular interest are scores of Iraqis ordered by immigration judges to leave the country, but who may have disappeared.

ABCNEWS' Brian Ross, Pierre Thomas and Steve Osunsami contributed to this report.