Berlin has called in 10,000 police and border guards to keep the peace during President Bush's visit to the city on Wednesday and Thursday. Tens of thousands of people demonstrated in Berlin Tuesday to protest U.S. policies, some of them shouting slogans calling the president a terrorist. And the German government fears further demonstrations could turn violent.

President Bush will meet German government leaders and speak to the German parliament in the historic Reichstag building during his two-day visit. He is expected to try to rally support for U.S. military action in the war against terror.

But some politicians, including pacifist members of the Green party and members of the former East German communist party (PDS), are among the organizers of mass-demonstrations, called to protest Mr. Bush's visit.

A West German Trotskyist, Winfried Wolf, who said he joined the PDS because it opposes war, said many Europeans, and not only those on the hard left, see a possible military attack on Iraq as dangerous. "I don't think war is the answer, especially when you mention chemical and biological weapons. I think this war could be much more brutal. And it could inflame the whole region," he said.

Mainstream demonstrators want the protests to be peaceful - sending a message that many Germans are strongly opposed to the way that the United States has conducted the war against terror since September 11.

But police fear that some of the demonstrations planned to oppose both military intervention in Iraq and the U.S. role in economic globalization could turn violent. They fear a hard core of about 2,000 protesters are intending to use violence. Many may travel to Berlin from outside Germany to try to repeat the kind of violence seen at big international meetings in places like Seattle or Genoa.

As early as Tuesday night, police were closing off sections of the city and standing guard around U.S. and British buildings in case of protests. They fear there may be diversionary attacks elsewhere in the city to draw some of the security forces away from the center.

Foreign Minister Joshka Fischer, himself a member of the Green Party, has urged demonstrators to remain peaceful, warning that violence would send the wrong message entirely.

And within the Social Democratic party, which governs the country in coalition with the Greens, there are fears that protests against President Bush will draw unflattering comparisons with the support shown for Russian President Vladimir Putin when he spoke to the German parliament last year, making much of his speech in fluent German.

The SPD chairman of the parliamentary Foreign Affairs Committee, Hans-Ulrich Klose, is bitterly opposed to the anti-American tone of the demonstrations. He wants Berlin to show its solidarity with the United States in the war against terror. He said Berlin, in particular, has to be thankful to the United States for its protection during the Cold War.

"We should not forget the basis of confidence between these two countries, and the Germans should not forget what the American presence meant during a lot of years, especially for this city. And especially for this city, a demonstration against an American president. I don't like it," Mr. Klose said.

Mr. Klose agrees with the far left that what he calls ill-considered action in Iraq could be destabilizing for key U.S. allies, especially Egypt and Saudi Arabia. He said he prefers a political solution if possible.

But he also supports showing Iraqi leader Saddam Hussein that the West will not shy away from military action if necessary. Mr. Klose said you cannot exclude the military option.

He said the Iraqi leader has to understand the threat of war is real.