The FBI is warning that al-Qaida may be planning a "spectacular'' terrorist attack intended to damage the U.S. economy and inflict large-scale casualties. The White House said Americans should remain vigilant, although it left the alert status unchanged.
"The American people are in many ways the first line of defense,'' said national security adviser Condoleezza Rice. She said the latest warning contained no new information, calling it instead a "summary of intelligence as we know it.''
White House spokesman Scott McClellan cited the lack of any intelligence about specific time, date, location or method of possible attack as the reason for keeping the nation's official terrorist threat level at code yellow, the middle of a five-level scale of risk developed after the Sept. 11, 2001, attacks.
"We continue to be on high levels of alert, we continue to take additional precautions,'' McClellan said.
The FBI warning was unusual because of its dire language.
Rice, briefing reporters at the White House on President Bush's trip next week to Europe to attend a NATO summit, said a lot is being done by the administration behind the scenes to protect "critical infrastructure'' around the country from possible attacks.
Safeguarding the nation against terrorism "is a central focus of this administration,'' she said. The campaign against terrorism is "a war that is many times being fought in the shadows, so it's not always on television screens,'' Rice added.
"The warnings that have gone out recently really are a summary of intelligence, not a new warning,'' she said
Gordon Johndroe, spokesman for the White House Office of Homeland Security, said that the new threats build on ones that the FBI and the White House have been making public since last month,
"Sources suggest al-Qaida may favor spectacular attacks that meet several criteria: High symbolic value, mass casualties, severe damage to the U.S. economy and maximum psychological trauma,'' says the alert, which was posted on the FBI's Web site early Friday after its existence was reported by The New York Times and The Associated Press.
The highest priority targets remain within the aviation, petroleum and nuclear sectors, as well as significant national landmarks, the warning says.
"Target vulnerability and likelihood of success may be as important to a weakened al-Qaida as the target's prominence,'' according to the warning.
"Thus, al-Qaida's next attack may rely on conventional explosives and low-technology platforms such as truck bombs, commercial or private aircraft, small watercraft, or explosives easily concealed and planted by terrorist operatives,'' it said.
The White House is sensitive to criticism from Democrats that the focus on Iraq is distracting Bush's attention from the broader war on terrorism. "He does not start his day on Iraq. He begins his day on the threat level ... and the war on terrorism,'' Rice told reporters.
Yet she acknowledged the war against al-Qaida is far from over.
"I don't think we can be certain of what role Osama bin Laden is or is not playing'' in the re-emergence of al-Qaida, Rice said. She walked through a long list of victories the United States and its allies have had in the war on terrorism, including the victory in its home base of Afghanistan and the disruption of cells in Buffalo, N.Y., and Germany.
Federal authorities previously have issued warnings for specific industries and national landmarks in general. But there is clearly worry that the danger of an attack is growing because of increased ``chatter'' picked up through intelligence channels, the continuing U.S. showdown with Iraq and the recently revealed audiotaped warnings believed to be from al-Qaida leader Osama bin Laden.
The government's additional precautions include unspecified "additional steps to ramp up our protection and prevention measures'' within federal agencies, he said. The FBI and other agencies also are communicating possible threats and assessments of risk to state and local law enforcement agencies and specific industries that could be targeted.
In recent weeks, the FBI has issued warnings about possible attacks on U.S. railroads and on the energy industry, as well as a more general warning about heightened risk during the Muslim holy month of Ramadan, which started Wednesday and ends Dec. 5.
"We're especially sensitive to timeframes which might be thought by the enemy to be a time when they might want to make a statement,'' Attorney General John Ashcroft said.
On Wednesday, the FBI told authorities in Houston, Chicago, San Francisco and Washington to be aware of threats against hospitals. Even though that threat was assigned low credibility by senior law enforcement officials, the FBI is preferring to err on the side of caution in terms of giving out information, officials said.
The idea is to increase vigilance among local police and people working in industries that are potential targets.
Last week, the State Department warned that Thursday's execution of Pakistani Aimal Khan Kasi in Virginia could lead to reprisals against Americans. Two days after his November 1997 conviction, assailants shot and killed four American oil company workers in Karachi, Pakistan. Kasi was executed for killing two CIA employees in a 1993 shooting outside the agency's headquarters.
The recent nightclub bombing in Bali, Indonesia, the assault on Marines in Kuwait and the attack on a French oil tanker near Yemen — as well as the U.S. strike on a car carrying suspected terrorists, also in Yemen — are described by several law enforcement officials as actions that point to an increased threat.