But the rare show of unity, at the first such gathering since the Iraq war ended, faltered when US Defense Secretary Donald Rumsfeld blasted Belgium over its controversial law allowing legal action against foreign officials.

Calling the lawsuits "absurd", Rumsfeld said the United States will oppose further spending on a new NATO headquarters here as long as senior US officials cannot visit the country without fear of prosecution.

"For our part we will have to seriously consider whether we can allow senior uniformed and civilian officials to come to... Belgium," he said.

Belgium was one of the main opponents of the Iraq war during the period leading up to the US-led offensive.

The US recriminations struck a sour note at a two-day meeting of defense ministers that officials had sought to portray as a model of harmony after the fierce disputes that rocked the alliance in February over the war in Iraq.

The ministers agreed to a new streamlined command structure as well as the operational concept for a 20,000-strong rapid response force to refit NATO for missions far outside its traditional geographic area.

"This is a massive change designed to make the alliance relevant and operationally effective," said George Robertson. "I cannot overestimate the importance of this fundamental change that is taking place."

"There are very positive signs that NATO is changing and is on the way to tranforming itself to meet new challenges," said British Defense Secretary Geoff Hoon, adding that staff numbers would be cut by 30 percent.

The decision came as Spain and Ukraine each committed to head a brigade of an 8,000-strong multinational division to help stabilize Iraq, which will be led by Poland with NATO's support, officials said.

A senior US official said NATO had a "near-death experience" in February, when three anti-war countries blocked the Alliance from providing defensive support for Turkey ahead of the Iraq conflict.

"It wasn't a near death experience," Robertson said. "It was messy. It was damaging.... (But) we have recovered quicker than most international organizations that were affected by that particular situation."

The overhaul of the command structure, which reduces NATO command elements from about 20 to 11, aims to move NATO away from a static defense of Europe to missions outside its traditional geographical area.

It puts all NATO operations under a single strategic command led by an American, NATO said.

A second strategic command based in Norfolk, Virginia will focus on training and other efforts to transform NATO militarily into a force capable of deploying rapidly to intervene in far-flung crises.

The centerpiece of the transformation effort will be a 20,000-strong NATO Response Force that is ready to deploy within days.

Plans call for beginning training and development of the force next autumn and having an initial force stood up within a year, officials said.

US officials pointed to NATO's recent agreement to take command of peacekeepers in Afghanistan and to support Poland in leading stabilization efforts in Iraq as evidence that the allies are getting back to business.

Spanish Defense Minister Federico Trillo announced that Spain will "co-lead" the division. Polish counterpart Jerzy Smajdninsky said the division will have a Spanish officer as its deputy commander.

But Rumsfeld's outburst against Belgium, shortly before his departure for Washington, cast shadows over the celebrations.

Implicit in Rumsfeld's comment was a threat to move the alliance headquarters from Brussels, which has hosted it since 1967 after France's break with alliance military structures a year earlier forced a move from Paris.

Robertson stopped short of saying the Belgian law could threaten NATO's continued presence in Belgium.

But he said: "If senior politicians and military commanders are inhibited from coming to NATO meetings here, then that has got profound implications for the way in which this Alliance operates."

WAR.WIRE