Washington -- Another terrorist attack on the United States or on U.S. interests abroad could come within the next week, the government warned yesterday.
But no one was able to say when, where or how it might be carried out.
“The administration has concluded, based on information developed, that there may be additional terrorist attacks within the United States and against United States interests over the next week,” Attorney General John Ashcroft said at a Washington news conference.
“The administration views this information as credible, but unfortunately it does not contain specific information as to the type of attack or specific targets.”
Another official told the New York Times last night that the warning was the product of both human and other types of intelligence about conversations that used language similar to what had been heard in intelligence intercepts before Sept. 11. There had been an increase, the official said, in the number of these references and the violence of the language used.
The alert is the second issued by the administration this month. On Oct. 11,
the FBI released a statement that the agency had received “certain information” indicating a terrorist attack could occur “over the next several days.”
Not long after that alert, anthrax-laden letters were received by congressional offices and news organizations. FBI Director Robert Mueller, appearing at the same news conference with Ashcroft, said there was no evidence linking the threats to the anthrax attacks.
Ashcroft said yesterday’s warning was relayed nationwide to 18,000 law enforcement agencies, many already on the highest state of alert.
NOTE DIVERTS PLANE
The heightened state of awareness was underscored yesterday when an American Airlines flight en route from New York to Dallas was diverted to Dulles Airport in Washington, D.C., after someone discovered what was thought to be a threatening note. The plane landed safely, and passengers evacuated by sliding down emergency chutes. Three people received minor injuries.
A government official, speaking to the Associated Press on condition of anonymity, characterized the note as a bomb threat. But bomb-sniffing dogs found no sign of a bomb aboard the plane.
Airport spokeswoman Tara Hamilton said the reaction was warranted considering “the international situation.”
That state of awareness affected the Bay Area, too, as U.S. Park Police closed off a section of the Presidio yesterday afternoon. Officers found two large trailers parked under the southbound Highway 101 access ramp and got some “suspicious information” from the vehicles’ leasing company, the park police said.
Officers set up a perimeter and brought in the San Francisco police bomb squad, which determined that there was no hazardous material in the trailers.
Meanwhile, local and state agencies said that they had received the warning from the Justice Department but that there was little more they could do.
“We’re still at the highest state of security following the Sept. 11 attacks,” said Mike McCarron, spokesman for San Francisco International Airport. “We’re just keeping our eyes open for any kind of threat.”
Oakland and San Francisco police departments said they felt prepared to handle any kind of emergency but were going over contingency and response plans anyway.
Bob Cassel, spokesman for the State Office of Emergency Services, said the warning was too vague to implement any specific action. As a result, he said, the OES is simply reiterating to its employees and other state workers that they should remain on alert.
Some critics complained that last month’s alert was overly vague and simply alarmed the public without giving any specific information that could help them avoid being targets of an attack.
Just last week, mayors attending the U.S. Conference of Mayors’ emergency summit on terrorism asked Mueller to give them more information before issuing warnings like the Oct. 11 alert, which forced them to spend extra money on security.
NO CAUSE FOR PANIC
But Ashcroft insisted that the American public is mature enough to understand the warning without panicking.
President Bush urged people not to let the threats unnerve them.
“The American people must go about their lives,” Bush said. “And I recognize it’s a fine balance. But the American people also understand that the object of any terrorist activity is to cause Americans to abandon their lifestyles.”
Counterterrorism expert Daniel Benjamin, a National Security Council aide in the Clinton administration, told the Los Angeles Times that authorities run the risk of having the public ignore their warnings if they put out too many alerts.
“That’s a real danger, but at the same time if you’ve got a credible source,
you have to go with it,” he said. “It would be politically disastrous if something happened and it was shown afterwards that they had foreknowledge.”
The FBI also alerted a number of federal agencies, including the Immigration and Naturalization Service, the Nuclear Regulatory Commission, the Environmental Protection Agency, the Federal Aviation Administration, the Department of Transportation and the Department of Energy.
In New York, police officials said they will employ heavy security at Yankee Stadium for tonight’s World Series game.
In the West Hollywood area of Los Angeles, where as many as 250,000 people were expected for Halloween celebrations tomorrow night, police plan to have officers patrolling by foot, car and horseback -- security measures already planned before yesterday’s advisory.
San Francisco Chronicle staff writers Stacy Finz, Henry K. Lee, Matthew B. Stannard and Jaxon Van Derbeken, as well as Chronicle news services, contributed to this report.