America gripped by fear of 'dirty bomb' attack

From the anti-aircraft missiles around Washington to government recommendations that families prepare bunkers in their homes against biological, chemical, radiological weapons, America is suffering its most acute bout of terror jitters since the attacks of 11 September.

From the anti-aircraft missiles around Washington to government recommendations that families prepare bunkers in their homes against biological, chemical, radiological weapons, America is suffering its most acute bout of terror jitters since the attacks of 11 September.

Nerves began to jangle last week when the new Department of Homeland Security raised its colour-coded threat alert to orange, denoting a "high" risk of an attack. Then came the latest purported Osama bin Laden tape, urging more suicide attacks against American citizens.

And yesterday, George Tenet, the CIA director, issued his grimmest warning yet, telling a Senate panel that a strike could come as early as this week, either in America or in the Arabian peninsula, perhaps involving a dirty bomb. The threat was "the most specific we have ever seen", he warned.

Hours earlier, the Pentagon confirmed that anti-aircraft Stinger missiles had been deployed around key sites in Washington, considered with New York the likeliest targets for the terrorists. But all along the eastern seaboard tensions are running high, and ordinary people are taking precautions.

"Duct tape, plastic sheeting, can openers; you name it, we're selling it," the manager of Candey's hardware store, just half-a-dozen blocks from the White House, said yesterday.

The run was sparked when Homeland Security officials issued a list of instructions on how to prepare for an emergency. Families are being urged to designate a "safe room" in their house, which could be sealed with plastic sheeting and tape.

They should stockpile three days of food and water, at the rate of a gallon per person per day, as well as blankets, torches, radios and spare batteries. Families should also have pre-arranged plans on how to keep in contact if separated.

The government insists the precautions are "prudent planning", just as people should prepare for natural disasters such as hurricanes, tornados or floods. But officials freely compare the measures to steps taken by Israel, whose citizens face the risk of attack every day.

The threat of a terrorist outrage in America in the next three weeks was "perhaps the equivalent of eight on a scale of one to 10", Tom Ridge, the Homeland Security Secretary, has said.

Most at risk now are not traditional targets such as airports and government buildings, but so-called soft targets, such as schools, banks, shopping centres and sports arenas. The attacks could be more insidious too, with bombs replaced by poison in the water supply.