Washington ? Seeking to counter European doubts about the U.S.-led war on terrorism, President Bush opened his weeklong trip Wednesday by warning allies they too could face attacks and urging their continued support for military action.

“Even though we’ve had some initial successes, there’s still danger for countries which embrace freedom, countries such as ours, or Germany, France, Russia or Italy,” Bush said as he departed the White House for a four-nation tour. “As an alliance, we must to continue to fight against global terror. We’ve got to be tough.”

Bush flew to Berlin, where he was to use an address to the German Parliament on Thursday to underscore the need for continued cooperation against terrorism. “I know America can’t win the war on terror alone,” he told the German TV station ARD.

But a stark reminder of European skepticism awaited him: Some 100 protests were planned across Germany on Wednesday and Thursday to coincide with his visit, and a demonstration in Berlin on the eve of his arrival drew as many as 100,000 people, most opposing any expansion of the war.

The president has not fielded questions from White House reporters in a week, a period in which it was disclosed that he learned last August that Osama bin Laden wanted to hijack U.S. airplanes, and did not answer queries after his brief statement Wednesday morning. But Bush submitted to a series of interviews from European journalists on Tuesday, eager to win hearts and minds there in advance of his trip to Germany, France, Italy and Russia.

Looking across a table in the Roosevelt Room at reporters from all four countries, Bush told them he surveys a threat-assessment report each morning, and added: “I am confident that I’ve read threats that were directed to the countries represented here.”

“The best way to secure our homeland, the best way for Italy to be secure, and other countries, is to find these killers, is to hunt for them, is to chase them down,” Bush later told Italy’s RAI television.

Throughout the sessions with European journalists, Bush molded his answers to fit his message on terrorism.

Asked whether the U.S.-European relationship was healthy, Bush said fighting terror “is a common cause that is a powerful force that unites us.”

Asked about the future of NATO, Bush said the war on terror requires just such a “collection of freedom-loving countries.”

His view of Russia? “We want Russia, our partner now in fighting terrorism, to have the means to continue the fight.”

Bush’s trip comes at a time when some Europeans are showing signs of skepticism and impatience with the terror war. After the Sept. 11 attacks on New York City and Washington, some 200,000 Berliners gathered at the Berlin Wall to show solidarity with the United States. Many wore shirts or held signs proclaiming “We are all New Yorkers,” adopting the phrase of John F. Kennedy’s 1963 “Ich bin ein Berliner” (I am a Berliner) speech in support of then West Berlin, an outpost surrounded by communist East Germany.

But in the first major demonstration Tuesday in Berlin, protesters carried placards that read “Pretzels instead of bombs” and “War is terror _ stop the global Bush fire.” The U.S. Embassy in Berlin sent out a message to Americans in Germany cautioning them about the demonstrations.

Bush told Germany’s ARD that Iraq _ a prime candidate for any expansion of America’s war _ is a menace to them.

“Iraq ought to be on the minds of the German people, and they ought to be on the minds of the American people, because the Iraq government is a dangerous government,” he said.

“This is a government that’s gassed its own people, this is a government that is not transparent, and this is a government we know wants to develop weapons of mass destruction,” Bush said. “They may have weapons of mass destruction; we just don’t know.”

He emphasized he has “no military plans on my desk that calls for, that plots out a military operation. I’m looking at all options.”

Bush also sought to soften his image among some Europeans as a go-it-alone leader with a distaste for alliances that are inconvenient to him.

“Listen, I believe in alliances,” Bush said. He used the word “collective” five times in two interviews.

Bush likened his plainspoken style to former President Reagan’s demand to Soviet leader Mikhail Gorbachev that he tear down the Berlin Wall. “He didn’t say tear down a couple of bricks. He said tear the whole thing down,” Bush said. “And I guess I tend to speak that way, too.”