L.A. Checked as Possible ‘Dirty Bomb’ Attack Target

When the nation went to a high-profile alert against terrorism in December, U.S. officials quietly dispatched Department of Energy investigators to five cities, including Los Angeles, to determine if they were threatened by radiological devices, according to an official familiar with the investigation.

But the search for so-called dirty bombs in Los Angeles, New York, Washington, D.C., Baltimore and Las Vegas failed to turn up any evidence of any such device, the official said Tuesday.

The search, according to the official, was part of the same increased security prompted by intelligence indicating that Al Qaeda was planning a new wave of attacks on the United States during the recent holidays.

But unlike the specific threats against airports and other potential terrorism targets, the official said, there was no certain information indicating that extremists had targeted the five U.S. cities for a radiological attack.

The search for radiological devices was first disclosed by the Washington Post in today’s editions. The paper reported that hundreds of nuclear and bioweapons scientists remain on high alert at military bases around the country, ready to fly to any trouble spot. Pharmaceutical stockpiles to treat biological attacks were loaded on trucks at key U.S. military bases as a precaution.

The recent intelligence indicating new terrorism threats against the United States prompted the Department of Homeland Security to raise the nation’s alert to its second-highest level on Dec. 21.

And during a tense week at several U.S. airports, including Los Angeles International Airport, federal authorities here and abroad initiated extraordinary security measures involving at least a dozen flights to the United States from Paris, London and Mexico City.

Those measures included the cancellation of at least a dozen flights and the escorting of commercial jetliners by U.S. fighter jets as they approached Los Angeles as well as Washington Dulles International Airport in northern Virginia.

Those security measures have been dramatically scaled back since last week, with no plans to cancel or intercept additional foreign flights into the U.S. unless there is new, specific, credible information of a threat, authorities said Tuesday.

Amid relief that the holidays had passed without a terrorist incident on U.S. soil, one federal official said the FBI and other agencies were weighing the possibility of scaling back some security measures to ensure that counterterrorism agents, analysts and others involved were not driven to exhaustion after three weeks of high alert.

“The question is how long can we continue at this level?” the official said.

At the same time, authorities acknowledged there were ample reasons to consider extending the heightened alert for at least another week and perhaps until the end of February.

“We felt before the holidays that there were three periods to worry about,” said one law enforcement official.

With the Christmas and New Year’s holidays over, the official said, counterterrorism experts are looking ahead to the Muslim holiday of Eid al-Adha, which begins in February, as a possible target period for extremists.

Last month, the London-based Arabic daily newspaper Al-Quds Al-Arabi reported that information sources linked to Al Qaeda warned that a new round of terrorism would be launched to coincide with Eid al-Adha, one of the two major Muslim holidays, according to the Middle East Media Research Institute.

That Dec. 10 report by the London newspaper also said a new videotape of Osama Bin Laden would be distributed shortly before the holiday. In recent days, a new tape purporting to show bin Laden has been aired around the world and is believed by U.S. officials to most likely be authentic.