BRUSSELS- As the United States pours troops into Afghanistan and boosts its role in the NATO force's command structure, Washington is trying to reassure its allies that it still wants the war to be a joint effort.

U.S. officials say they want to stick with NATO in Afghanistan for political and practical reasons, even though waging war as part of the alliance brings frustrations such as limits on the use of different nations' forces.

In an effort to turn the tide against a resurgent Taliban, Washington is deploying more than 30,000 troops to Afghanistan this year to reach a total of 68,000 by autumn -- a presence about twice as large as all other NATO members combined.

U.S.-led forces toppled Afghanistan's former Taliban regime in 2001 after the September 11 attacks on New York and Washington, which U.S. officials say were planned from al Qaeda safe havens on Afghan territory.

With insurgent violence at its worst level since then, U.S. officials acknowledge they are not winning in Afghanistan and the administration has declared the war its military priority.

U.S. Defense Secretary Robert Gates, who has been blunt in his criticism of NATO nations for not committing more troops to Afghanistan, was keen to strike an upbeat note after a meeting of alliance defense ministers in Brussels on Friday.

I would not minimize the importance of 32,000 NATO and partnering troops in Afghanistan and the role that they and their civilians and their development people are playing in virtually every part of the country, he said.

At the meeting, ministers agreed to a new command structure for the force which will increase the influence of U.S. generals.

While the United States has held the top command post for years, the new plan will create an extra headquarters, headed by a U.S. general, to oversee day-to-day operations.

NATO will also create a mission to train Afghan security forces, commanded by another U.S. general who already runs a similar operation.

Although Washington is clearly playing an increasingly dominant role, U.S. officials have stressed they are choosing to operate within the NATO structure rather than go it alone.

In a gesture intended to emphasize U.S. respect for NATO allies, Gates invited U.S. Army General Stanley McChrystal, the incoming top commander for the Afghan force, to meet the ministers on Friday.

STRONG SIGNAL OF SUPPORT

U.S. officials have often expressed frustration that their allies have not sent more troops to Afghanistan and that many nations also place restrictions, known as caveats, on their forces which prevent them taking on more dangerous missions.

It would be much better if we had an operation in which everyone participated to the same extent, said a senior U.S. official, speaking on condition of anonymity.

The political reality is that that's not the case so we make the best out of the situation that we have.

Gates said the presence of a big international coalition also sent a strong signal of support to the Afghan government as it struggles to establish its rule.

Afghanistan