US intelligence officials have told members of Congress it is highly probable that terrorists associated with Osama bin Laden will try to launch another major attack on American targets in the US or elsewhere in the near future.
Based on what officials described as credible new information, the FBI and CIA have assessed the chances of a second attempt to attack the US as very high, sources said on Thursday.
At a briefing, one intelligence official said there is a "100 per cent" chance of an attack should the US strike Afghanistan, in response to a senator's question about the gravity of the threat.
One senior official said some of the new intelligence is "very real". But the official cautioned that some of it may be a bluff or even intentional disinformation to discourage the US from retaliating for the September 11th attacks.
The new information is worrying enough that officials at the White House, the Justice Department and the State Department have huddled in recent days to figure out the best way to communicate their concern to the public.
The concern is based on intelligence from sources in England, Germany, Afghanistan and Pakistan, according to a source familiar with what congressional intelligence committees have been told. Egyptian, Somali and Pakistani elements of bin Laden's network are thought to be involved.
Members of the intelligence committees declined to comment on the briefings, which are classified. But their public comments, and remarks by Attorney General, Mr John D. Ashcroft on Sunday, highlight the danger.
"We have to believe there will be another attempt by a terrorist group to hit us again," Senator Richard Shelby (Ala.), ranking Republican on the Senate Intelligence Committee, said on Thursday. "You can just about bet on it. That's just something you have to believe will happen."
Senator Shelby declined to discuss specific intelligence information on the plans of bin Laden's al- Qaeda terrorist network that were provided in a classified briefing on Tuesday by counter-terrorism officials from the FBI, CIA and the Defense Intelligence Agency.
Mr Ashcroft warned earlier this week that there is a "likelihood of additional terrorist activity", and that the "risks go up" once the US responds with military action. "We think that there is a very serious threat of additional problems now," he said. "And frankly, as the United States responds, that threat may escalate."
The Justice Department sought to play down that warning slightly on Monday, after it received more media attention than officials had expected.
"Ashcroft's and Powell's \Secretary of State\ people and the White House are working on how to word their warnings," a source familiar with multi-agency discussions said. "The government doesn't want to panic people." But, he added, "the government is definitely preparing for a counter-strike by bin Laden."
Government officials fear attacks at any of hundreds or thousands of locations, including symbols of American power and culture, such as government buildings in Washington and entertainment centres. They are concerned about truck-bomb and car-bomb explosions that could be detonated near natural gas lines, power plants and other sites.
The FBI has taken a particular interest in crop-dusting aeroplanes for fear they could be used in a chemical or biological weapons attack. Mohammed Atta, one of the suspected leaders of the September 11th attack, expressed a keen interest in the planes. Zacarias Moussaoui, a French-Moroccan man in custody as a material witness, reportedly had materials about crop dusting when he was detained in August.
The over-riding goal, a senior official said, is to make the US a "hard target" for terrorists.
But US intelligence and law enforcement agencies do not have specific information on the nature of future attacks. The Coast Guard is boarding and searching ships in New York, Boston and other harbours, and security has been stepped up around nuclear power plants, oil pipelines, refineries and other potential targets.
The FBI has found no links between any of the 19 alleged hijackers or their possible accomplices and any of the 1,000 to 2,000 suspected terrorist sympathisers in the US, including known al-Qaeda supporters. The terrorists responsible operated as a closed unit and there may be other such cells as yet undetected, some members of Congress were told.
"The investigative case has to take a back seat to preventing the next terrorist act," a senior law enforcement official said. "That comes right from the top, from the president of the US on down."
In preparation, the FBI has a plan in place to go "full tilt" for 72 hours whenever the President decides to make a move against bin Laden, al-Qaeda or the Taliban, the official said. At the investigation's command centre in FBI headquarters, a team of analysts and agents has been working around the clock sifting through reports of potential threats.
Officials acknowledge it is difficult to understand the motivation behind some of the threats.
In response to threats from bin Laden's network detected in June and July, for example, officials abandoned some US embassies and moved Navy ships in foreign ports out to sea. Now, they have concluded, the threats may have been disinformation to occupy their attention, or to allow bin Laden operatives to observe US counter-terror lockdown methods.
Senator Shelby said law enforcement agencies believe terrorists will do something unexpected, and thus they are trying to think "out of the box" to anticipate what might be ahead. However, he noted, bin Laden has been known to return to the same targets repeatedly, such as the World Trade Centre, which terrorists with possible ties to him bombed in 1993. In 1999, a terrorist cell linked to bin Laden was thwarted in what one participant later testified was a plot to bomb Los Angeles airport.
A senior government official said on Thursday that if al-Qaeda follows its normal pattern, "other attacks are in various stages of planning". The US embassies in Kenya and Tanzania, bombed in 1998, were first surveilled as targets in 1994, according to court testimony earlier this year.
The official said bin Laden's organisation "likes to mix tactics and targets."
Therefore, more airplane hijackings seem less likely, because security has been increased. Ground-based operations seem more probable.