By Kevin Anderson
BBC News Online in Washington
Some US foreign policy experts see potential troubles ahead
The addition of 10 countries to the European Union has garnered little attention in the US, overshadowed as it was by events in Iraq and domestic issues.
But US foreign policy experts view the enlargement of the EU as a positive development for the world's lone superpower.
The new member states are viewed as more pro-American - part of Donald Rumsfeld's "new Europe".
And some experts think the new member states could energise the EU economy with greater liberalisation and higher rates of growth, which would be good for US exports.
But with transatlantic relations still strained after the divisive lead up to the war in Iraq, some American foreign policy experts also see troubles ahead for US-EU relations.
Marian Tupy, at the free-market Cato Institute, said enlargement is unambiguously good for the US.
"The new countries joining the EU are more pro-American - not necessarily the public, but their governments," he said.
The US continues to be the biggest player in Nato.
These countries see Nato as the main counterbalance to Russia in the region, which continues to be these countries' main foreign policy concern, Mr Tupy said.
"They look to the US for security guarantees, and they will oblige the US when it comes to foreign policy," he said.
The Poles and Hungarians have all sent troops to take part in the US-led efforts to stabilise post-war Iraq - as did the Romanians, who are hoping to join the EU soon.
And Mr Tupy sees this pro-American stance carrying on even after the states have joined the EU.
However, Charles Kupchan, former National Security Council member on European affairs under President Bill Clinton, sees pro-American sentiment on the wane in central Europe.
"I think central Europeans are rethinking their strategy of being America's new closest ally," he said.
"I don't think it got them the rewards they were expecting," he added.
The US is also dramatically decreasing its strategic engagement with Europe.
"They thought security would be provided by Uncle Sam, and it's not happening," he said.
'Counter-balance to US power'
It is no secret that many European leaders want the EU to develop into a counter-balance to US economic and political power in the world.
Views vary widely in Washington as to whether enlargement will help or hinder the EU in achieving this goal, and whether this is a positive or negative development for the US.
The conventional wisdom in Washington is that enlargement will make the EU more unwieldy and prevent it from becoming a strategic counter-balance to the US, said Mr Kupchan.
Mr Tupy said that some in Washington think the US should try to remain the world's lone superpower.
However, his view is that the US does not have the power or resources to maintain a "uni-polar world".
Some see the new EU as more unwieldy - but also more centralised
"If Europe grows to be another pole in the world and also assumes some of the responsibilities, like dealing with issues at its periphery, we think that is a good thing," he said.
And with the new member states being friendlier towards the US, he sees less of a chance of Europe developing into anti-American power.
Mr Kupchan believes that although the new additions will make the EU more unwieldy, it will also force forward reforms to give union a more unitary and centralised character.
And despite the more pro-American bent of the new members' governments, he said: "I think that the idea that the new members will make the EU more atlanticist are overstated."
The centre of gravity in the EU will remain in Brussels, Berlin, London and Paris, he added.
The US and Europe are entering an historical watershed in terms of Atlantic relations, Mr Kupchan said.
"What is perhaps the most revolutionary accomplishment in 20th century - an Atlantic zone of peace where the balance of power does not operate - that zone is at risk," he said.
"Americans and Europeans should realise that the stakes are high, and both sides ought to do what they can put relations back on sound foundation," he added.