The first of seven long-range jets - each capable of carrying Cruise missiles - landed at RAF Fairford in Gloucestershire on Sunday afternoon.

Defence Correspondent Mark Laity: Bombers will play a key role in any airstrikes

Several hundred people lined the perimeter fence of the airfield to watch the giant aircraft complete their low-level approach over the Cotswold countryside.

The rain, which had earlier swept the runway, cleared in time for the first of the aircraft - each with a wingspan about the same as a jumbo jet - to touch down smoothly at around 1300 GMT.

The massive bomber deployed a parachute to slow itself down, before taxiing to a special holding area.

The "Stratofortress" aircraft took eight hours to fly in from their Barksdale air base in Louisiana, USA.

They are a mainstay of the US military - deployed in Vietnam and Operation Desert Storm - and are specialists in high-altitude "carpet-bombing".

Military action

A US military spokesman said: "The deployment is another in the steps US forces are taking to be prepared in the event a decision is made to respond militarily to the situation in Kosovo."

Some 400 Nato warplanes - including eight Harrier GR7 jump-jets stationed in Italy - are already on stand-by in Europe.

Nato says it will take military action against Yugoslavia if the talks between international mediators at Rambouillet, France, end without agreement before Tuesday's deadline.

Robin Cook: 'Still a long way to go'

But the 1,200 international monitors of the Kosovo Verification Mission would have to be withdrawn from the province before air strikes could begin.

A 1,800-strong international extraction force - including 390 British soldiers from the 1st Battalion, the King's Own Royal Border Regiment - is on stand-by in Macedonia in case they need rescuing.

UK Foreign Secretary Robin Cook said there was still a long way to go before agreement could be reached.

There is some agreement on political changes but the main sticking point is thought to be Serbia's refusal to allow a Nato peace-keeping force in Kosovo.