People in the West will have to learn to live under permanent threat from Osama bin Laden's agents, who could strike with "dirty" nuclear bombs as well as chemical or biological weapons, a French terrorism expert has said.
Mr Roland Jacquard, an adviser to the United Nations Security Council and author of a book about Washington's prime suspect for suicide air attacks on US cities three weeks ago, believes his supporters are ready to attack again.
But they could also lie low for months or even years, waiting for governments to drop their guard.
"It is the nature of bin Laden's organisation to plan attacks in advance, to choose . . . the commandos that will carry them out and give them the ability, technology and financing so they can act without needing orders or having to return to the bases in Afghanistan," he said.
Mr Jacquard, who heads France's International Terrorism Observatory, said bin Laden had the capability to launch a chemical attack and had obtained enough radioactive material to create a "dirty" nuclear bomb using conventional explosives.
"He certainly doesn't have the technology to make a nuclear bomb . . . but he has been able to get suitcases of radioactive material from mafia in former Eastern Bloc countries," he said.
Mixed with conventional explosives, this could spread radiation over a wide area.
Despite the best efforts of US and European secret services to crack the Saudi-born millionaire's network, Mr Jacquard said agents might well remain "dormant" for years, like many of the hijackers who carried out the attacks on the World Trade Centre in New York and the |Pentagon in Washington on September 11th.
"The more that is done to destroy bin Laden's organisation, the more they will try to carry out the plans they have already," he said.
Mr Jacquard said that in this climate, with a long fight ahead to eradicate an enemy that is almost impossible to identify, Americans and people living in countries on friendly terms with the United States would have to get used to living under siege.
"Since the attacks on the World Trade Centre, nothing will be the same as before. People in the mass-market consumer societies of the United States and Europe will have to live like people in countries such as Israel, under permanent threat."
The United States, France and many other countries have stepped up security in public places, deploying soldiers at airports and train stations and sealing rubbish bins.
In his book on Osama bin Laden, finished months ago but published just days after the attacks which killed thousands of people, Mr Jacquard said bin Laden had a veritable arsenal of weapons.
"In terms of biological terrorism, he has some extremely harmful products, but they are difficult to handle," he said.
"It is in chemical weapons that things are really advanced, with a team of men training all the time in laboratories in Afghanistan."
Mr Jacquard added that bin Laden had almost certainly thought of the simplest plan of all - to attack a nuclear power station or chemical site, thereby unleashing huge and devastating damage with little effort.