The US has criticized Germany and other European allies that have refused to allow their troops in Afghanistan to be deployed to the southern heartland of Taliban insurgency alongside US, British, Canadian, Dutch and other contingents. Defense Secretary Robert Gates has proclaimed himself "a nag on the issue."
European leaders have expressed skepticism about winning the Afghanistan mission on the ground or that NATO has the capabilities it needs to succeed. Moreover, they face public opposition about the war and pressure for an exit strategy.
Europeans also say the US has been too preoccupied with Iraq and has not put the proper focus or devoted enough political capital on Afghanistan.
"Europeans are often quick to dismiss the Afghan mission as an unnecessary part of President Bush's war on terror," said Philip H. Gordon, a former director for European Affairs at the National Security Council and now a senior fellow at the Brookings Institution. "But I believe they can be persuaded that the mission is actually in Europe's own strategic and humanitarian interest."
Some of the differences appear to be narrowing. French President Nicolas Sarkozy has pledged to deploy more troops to fight the Taliban if Afghans also get more responsibility and there is better coordination of nonmilitary efforts.
Bush, in a pre-trip interview, said it would be hard for any nation to trump Britain as "our greatest ally" - particularly given its strong backing in Iraq.
But Bush he said the relationship with France "is changing for the better and President Sarkozy gets a lot of credit for that."
Sarkozy's promise of more French troops in Afghanistan "will pretty much ensure that this (NATO) conference is a successful conference," the president said.