If you want to have systems that can deal with such a threat, you don't wait until they're pointed at your heart

Colin Powell

Mr Powell did win a minor victory as Nato ministers omitted from their final joint statement any reference to the 1972 Anti-Ballistic Missile Treaty.

Last year's joint statement favoured strengthening the ABM treaty calling it the "the cornerstone of strategic stability."

The Bush administration wants to scrap or heavily modify the treaty, which prohibits development of national missile defence systems by either Moscow or Washington.

Pushing ahead

Mr Powell said he hoped to win more converts to the missile defence plans later and would follow through on a promise to consult closely with allies.

In the interim, he said, the US administration would press ahead with planning.

"If you want to have systems that can deal with such a threat, you don't wait until they're pointed at your heart," he said.

US wants protection from "rogue states"

The BBC's Jonathan Marcus says that the Americans clearly believe that Nato is slowly coming round to their way of thinking.

On other issues, the alliance's North Atlantic Council, Nato's top policy-making unit, asserted that it was "not advisable at this time" to consider major reductions or reorganisation of peacekeeping operations in Bosnia.

Nato officials said they expect to cut about 10% to 15% of the peacekeeping force of 21,000 - of which 3,300 are Americans.

"The job is not yet completed," Nato Secretary-General Lord Robertson said.

Fears for Macedonia

Nato leaders also expressed alarm at rising violence and political instability in Macedonia.

They urged the government to use "proportionate force" in maintaining order and said rebels who use violence should be excluded from the negotiating table.

Tuesday's statement on missile defence does not make the job any easier for Bush administration officials to sell the plan.

US Defence Secretary Donald Rumsfeld will try again next week when he meets with other Nato defence ministers.

And the subject is certain to top the agenda at the heads of state Nato summit in Brussels, on 13 June, which President Bush will attend.