BRUSSELS, Belgium - President Bush, hoping to thaw relations with European leaders skeptical about U.S. involvement in Iraq and the Middle East, pressed today for greater trans-Atlantic relations. "In a new century, the alliance of America and Europe is the main pillar of our security," he said.

Bush pledged to move forward to long-running conflict between the Palestinians and Israelis and "raise the flag of a free Palestine."

"The world must not rest until there is a just and lasting resolution to this conflict," Bush said.

Belgium Prime Guy Verhofstadt, who introduced Bush, said the U.S.-led invasion was divisive, but with problems in Africa and other parts of the world, "It makes little sense arguing about who was right."

Turning to another volatile spot in the world, Bush called on Syria to withdraw its forces from Lebanon. As Bush spoke, thousands of opposition supporters in Beirut shouted insults at Syria and demanded the resignation of Lebanon's pro-Syrian government, marking a week since the assassination of Rafik Hariri, Lebanon's most prominent politician.

Syria must end its occupation of Lebanon, Bush said to applause.

"The Lebanese people have the right to be free, and the United States and Europe share an interest in an independent, democratic Lebanon," he said, adding that if Syrians stay out of Lebanon's parliamentary elections in the spring, the vote "can be another milestone of liberty."

Bush also continued to push Iran to end its nuclear ambitions. He said the United States was working with European allies Britain, France and Germany in the "early stages of diplomacy." Bush did not, however, note that the United States is not fully backing the Europeans' approach to offer Iran economic and political incentives not to develop nuclear arms.

"The results of this approach now depend largely on Iran," Bush said. "The time has arrived for the Iranian regime to listen to the Iranian people and respect their rights and join in the movement toward liberty that is taking place all around them."

Bush's speech, at Concert Noble, a 19th-century government building used for banquets and meetings, was aimed at both U.S. and European audiences. The president began his five-day European trip in Brussels, home to both the European Union and NATO. He later travels to Germany and Slovakia where he will meet, for the first time since his re-election, with Russian President Vladimir Putin.

The president has been pushing Putin - some say not strongly enough - to work toward, not away from, democratic reforms and transparency in government.

"We recognize that reform will not happen overnight," Bush said. "We must always remind Russia that our alliance stands for a free press, a vital opposition, the sharing of power and the rule of law."

"The United States should place democratic reform at the heart of their dialogue with Russia," he said.

Despite Bush's appeal to bury past differences, divisions remain - over postwar Iraq and other issues, including the U.S. decision not to enter the Kyoto climate change treaty, which many European nations supported.

Bush said the answer lies in "the power of human ingenuity."

"Emerging technologies such as hydrogen powered vehicles, electricity from renewable energy sources, clean coal technology will encourage economic growth that is environmentally responsible," he said.