PRAGUE, Czech Republic - President Bush said yesterday that NATO states should decide individually whether to join the United States in any military action against Iraq, but said it was possible that Saddam Hussein's regime could be disarmed peacefully.

In a speech to students yesterday, Bush said the threats of terrorists - including those who could be aided by Iraq - were as dangerous as those faced by "your grandfathers and grandmothers."

"Great evil is stirring in the world," Bush said.

And, he suggested, it was time for European countries to repay the United States for its role in World War II.

"The commitment of my nation to Europe is found in the carefully tended graves of young Americans who died for this continent's freedom," Bush said.

Earlier, at a news conference with Czech President Vaclav Havel, Bush said, "If the collective will of the world is strong, we can achieve disarmament peacefully." But if Hussein does not disarm, he added, "the United States will lead a coalition of the willing to disarm him."

"But one thing is certain," he said. "He'll be disarmed, one way or the other, in the name of peace."

NATO leaders were gathering to vote seven more countries into the alliance today. That expected move - the largest expansion since NATO's creation in 1949 - has been largely overshadowed by the prospect of war with Iraq.

American F-16s provided security in Czech airspace, while 15,000 police and military personnel guarded the Prague streets, both to defend against terrorist attacks and to control anti-war protests that began on a small scale yesterday and are expected to grow today.

Though Bush tried to ease anxieties that he was bent on war, there is strong sentiment in Prague and throughout Europe - evidenced by street protests that have attracted thousands in recent weeks, including a half-million in Florence, Italy - that military action is merely a matter of time.

"It's easy why people are against war on Iraq," said Milan Smrz, 54, who planned to be among thousands of protesters expected at Prague's Wenceslas Square today. "We lived under communism, and communism was a war against the people. Now we have Bush leading the way to war again."

Bush is seeking NATO approval of a military strike against Iraq if he deems it necessary, but he is not asking the alliance, as a whole, to take part.

The White House has confirmed it has been polling foreign leaders in recent days to see which countries can be counted on to join an attack against Iraq if United Nations inspectors are thwarted.

Despite the United Nations resolution that put inspectors back in Baghdad on Monday, key U.S. allies remain divided over what would constitute a trigger for a military attack on Iraq. Germany has said it will not take part in any military action.

More than 40 heads of state are in Prague for the summit, though the public will see none of them.

Their hotel is cordoned off by Czech soldiers standing shoulder to shoulder. Snipers are atop surrounding buildings, and helicopters hover over Prague constantly. Small protests of several hundred people have been kept far from the dignitaries, some of whom arrived last night. None of them has taken part in public events other than the brief speech Bush gave to students in which he called on NATO countries to contribute more militarily to the alliance.

The leaders' seclusion, said Irena Vodakova, 42, a teacher from Prague who planned to protest today, is frustrating - and partly responsible for what she sees as an inevitable march toward war.

"They're discussing war and peace, but there is no reason for a politician to listen to someone like me, because this war is about them," she said. "They have their meetings, say nice things to each other, but they don't know or don't care that people like me are absolutely opposed to war. It is all about power, especially with Bush, whose attitude is, 'I can decide for you.' Well, I don't want him deciding for me."

Havel, who often attaches a small drawing of a heart to his signature, had a giant, neon red heart placed atop the Prague Castle, a medieval building that last night was the scene of a black-tie dinner for the heads of state.

He said the heart represented peace and friendship among countries. Havel said he hoped war with Iraq could be avoided by Hussein's surrendering any weapons of mass destruction. But, he added, if "the need to use force were to arise, I believe NATO should give honest and speedy consideration to its engagement as an alliance."

Diplomats said this week that a summit statement was being negotiated that would demand Iraq cooperate fully with weapons inspectors

Bush, who did not seek NATO military aid for the war in Afghanistan, rejected arguments that the alliance has become irrelevant, but he said the war to topple the Taliban clearly showed why the alliance needed reform. NATO could not be used, he said, because it was "limited" and unable to carry out quick strikes.

Partly in response to Afghanistan, the summit will also focus on plans to create a force of 21,000 combat-ready troops who could quickly deploy around the world.

The countries expected to be invited to join NATO are the Baltic republics of Estonia, Latvia and Lithuania, along with Slovenia, Slovakia, Bulgaria and Romania.

Bush said NATO must adapt its military strategy to focus on terrorism and deploying to trouble spots.

NATO had been conceived as a defensive alliance to combat invasion.

"The enemy is not Russia," Bush said. "The enemy is global terrorists who hate freedom. And together we can work to defeat that enemy in the name of freedom."