At a NATO meeting in Brussels, defense ministers have agreed the alliance needs to be better prepared to respond to the pervasive spread of weapons of mass destruction - a threat Secretary Donald Rumsfeld describes as urgent and far worse than previously thought. These threats could result in NATO members becoming more involved in the fight against terrorism.

"Ladies and gentlemen, the world is changing, and so is NATO," Mr. Robertson said.

NATO Secretary-General George Robertson, speaking after a meeting of alliance defense ministers who heard U.S. Defense Secretary Rumsfeld offer a dire warning - that threats of nuclear, chemical and biological weapons falling into the hands of terrorists are actually worse than the facts now suggest.

"This threat is not theoretical. It is real; it is dangerous. If we do not prepare promptly to counter it, we could well experience attacks in our countries that could make the events of September 11th seem modest by comparison," Mr. Rumsfeld said.

An outline provided to reporters on what he told fellow ministers behind closed doors suggests Mr. Rumsfeld was emphatic, saying what happened in the United States should make other countries ask what they need to do now to prevent a similar attack in Europe.

NATO secretary-general Robertson all but conceded the alliance is not entirely equipped to meet that threat. "There is doctrine that deals with the use of nuclear weapons. There are actually methods of protection against some chemical weapons, and we have got some capability in that area. But we have to face the fact that biological weapons, germ warfare is now coming on to the agenda for both individual terrorists and perhaps for terrorist states," Mr. Robertson said.

Defense Secretary Rumsfeld advised fellow NATO members not to wait for absolute proof before acting against terrorist threats, suggesting the alliance may soon find itself breaking with tradition and becoming involved in military action far beyond European soil.

"The only defense is to take the effort to find those global networks and to deal with them as the United States did in Afghanistan. Is that defensive or offensive? I personally think of it as defensive. We had no interest in doing anything in Afghanistan. It was not on the radar scope," Mr. Rumsfeld said.

All of this, though, will require increasing military budgets, while at the same time reducing the capabilities gap between the U.S. military and those of Europe. Secretary Rumsfeld wrapped up a news conference here Thursday with a final warning: the way NATO has done business for the last half century can no longer provide a defense against the kind of terrorists and weapons that will inevitably strike again, this time, perhaps, in Europe.