Nicholas Burns said NATO defense ministers meeting here were likely to instruct the alliance military leadership to report back in February on how to bring NATO and US military operations under a single NATO command.

"That's the direction the alliance has been heading for many months now, and it will likely be the result of tomorrow's discussion," the US ambassador to NATO told reporters in Romania.

He suggested that the two forces could be brought under a NATO command quickly once the plans have been drawn up.

"It could be 2005, it could be 2006, it depends on how things go. It really depends on what the military leaders will tell us: how would you do this, how difficult would it be, on what basis would it be," he said.

US Defense Secretary Donald Rumsfeld will press his colleagues for the planning as well as swifter action on expanding NATO's existing 9,000-strong International Security Assistance (ISAF) peacekeeping force.

NATO recently completed the first phase of an expansion of the force from Kabul to relatively trouble-free areas in northern Iraq, but a second planned one into western Afghanistan has stalled.

"I know the US, Secretary Rumsfeld and others will be pushing for the European allies to put their men, women, materiels, assets into the west to establish these provincial reconstruction teams," he said.

ISAF has four small so-called provincial reconstruction teams that are designed to extend the reach of the Afghan central government beyond Kabul.

The United States has nearly 20,000 of its own troops in Afghanistan. They are still pacifying the country's southeastern border regions three years after the fall of the Taliban regime in a US-led invasion.

Rumsfeld first floated the idea of having NATO taking over all military operations in Afghanistan in December, but until now it has remained in the background while NATO struggled to expand its Afghan peacekeeping effort.

If NATO were to take the lead role in Afghanistan it would relieve the stress on US forces, which are tied down by a stubborn insurgency in Iraq.

It also would mark a further expansion of NATO commitment's outside of its European treaty area.

The US push comes just days after presidential elections in Afghanistan. NATO deployed extra troops from its rapid response force to help protect the elections.

Burns cautioned that the issue of merging the two forces was "enormously complex" and no decisions would be taken at the informal meeting of defense ministes at this ski resort in the Carpathian Mountains.

"But I think there will be a number of people who will support, and we will support maybe a direction to the military leaders of the alliance to go and look at this question, and decide how we can best do that," He said.

"Give us the sense of how you can put together these two missions over the course of the next year. Give us the options and we will come back at the next meeting, which is in Nice (in southern France), the first week of February 2005," he said.

Burns said a "lot of thinking" had been done on the issue, and the NATO military has undertaken some informal planning already.

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