Number one remains Iraq. France and Germany still refuse to allow military personnel to enter Iraq. Any contributions they make to training will take place in countries neighbouring Iraq.
Number two is Iran. The US is intensely suspicious of the recent European deal that elicited promises from Tehran - a "totalitarian" regime, according to Condi Rice - to renounce uranium enrichment in return for assistance with non-military nuclear projects. The European position, as enunciated by the German defence minister last week, is that Iran will "only abandon its nuclear ambitions if _ its legitimate security interests are safeguarded". This does not play well in Washington, where plans were quite recently afoot for air strikes against Iranian nuclear facil ities. At the very least, the US wants to put the case for sanctions against Iran before the UN security council.
The biggest source of tension, however, may relate to China. The Europeans plan to lift the arms embargo imposed in 1989 after Tiananmen Square. The Americans oppose this, but their opposition is a symptom of a deeper suspicion of what Europe is up to in Asia.
http://www.guardian.co.uk/comment/story/0,3604,1418969,00.html