Bush met at the White House with German Chancellor Angela Merkel, who holds the rotating presidencies of the EU and the Group of Eight (G8) industrialized nations, and European Commission President Jose Manuel Barroso.

The leaders were not expected to agree on concrete steps to battle global warming, but were to describe the problem in a joint statement as a common challenge requiring "urgent, sustained, global action," a US official said.

They were also slated to push ahead with lowering trade barriers and inking an agreement aiming to erase differences on regulation -- in the automobile or pharmaceutical sectors and on intellectual property.

They were also expected to sidestep four-year-old disputes over the war in Iraq and stress their cooperation on issues like Iran's nuclear ambitions, the Middle East peace process, violence in Darfur, and worries about Russia.

Russia worries

Washington and Brussels worry that Moscow has abandoned pledges to enact democratic reforms and have backed Kosovo formally becoming independent from Serbia -- something fiercely opposed by Russia.

The leaders were also expected to discuss Russia's announcement that it was suspending its participation in an arms treaty limiting the number of military forces in Europe, in apparent retaliation over US plans to deploy a missile shield there.

On climate change, Merkel hoped that the annual US-EU summit in Washington would bridge some transatlantic gaps before the beginning of June, when she is to host the summit of eight industrialized countries back in Germany.

Climate

The joint US-EU statement on energy security and climate change, obtained by AFP, was to state that "addressing these issues requires urgent, sustained global action and an integrated policy approach, using a wide range of regionally, nationally or internationally defined policy tools and measures."

The 27 EU members agreed in March to reduce greenhouse gas emissions by at least 20 percent by 2020, based on 1990 levels. Germany's proposal was a more aggressive 40 percent cut.

The US ambassador to the European Union, C. Boyden Gray, has warned against high expectations from Monday's summit, saying it would "not be a defining moment" but only "one part of the journey."

Bush has refused to accept any imposition of limits on greenhouse gas emissions, saying it would harm the US economy.

Bush has pointed out that without the cooperation of the rapidly booming Chinese and Indian economies, emission cuts by other countries are in vain. And he has pressed for the development and use of new technologies.

At a joint news conference in the Rose Garden, the European side said it felt progress was made on the issue, despite an absence of concrete steps the EU and the United States can take together to address the problem.

"I really welcome the fact that there was progress in this meeting," said Barroso. "We agree there's a threat, there's a very serious and global threat. We agree that there is a need to reduce emissions. We agree that we should work together."

Planes, visas and Iran

In one key step, the two sides were expected to sign a US-EU "open sky" accord on freeing up transatlantic air travel, which would allow airlines to fly anywhere in Europe or the United States beginning in March 2008.

Europeans hope that the United States will abandon its visa demands for Eastern European countries which have recently been inducted into the European Union.

During three joint work sessions, Bush, Merkel and Barroso were also to bolster cooperation regarding Iran and its nuclear ambitions, the status of Kosovo, and on the proliferation of "terror." Iraq and Afghanistan are also to figure on the agenda.

EU diplomacy chief Javier Solana said Friday he would highlight the need for the United States to break its more than 25 years of silence with Iran and establish a "channel of communication" on all subjects.

Observers agree that the summit rarely provides breakthroughs, and is even less likely to show any this year, as some European countries await political changes and the US campaigning for president in 2008 is well underway.