Two-speed NATO  

Proposals for a permanent NATO combat presence in eastern Europe were blocked by Germany and some other alliance members. Instead, NATO intensified exercises, rotating troops through the region and set up a command headquarters for a rapid reaction force in north-west Poland.

Sources close to the government in Poland, and other states in the region, said that response persuaded them they could not fully rely on NATO, and that their best bet in the event of an attack was that the US military would come to their aid.

At a NATO summit in Wales last year, agreement was reached on "pre-positioning" military equipment in eastern Europe, but the Pentagon's plan appeared to go further and faster than measures envisaged by the alliance.

The initiative could force some former Warsaw Pact countries now in NATO to make uncomfortable choices.

Bulgaria and Hungary both say they are committed members of the alliance, but they have maintained close cultural and commercial ties to Moscow, and may not want to jeopardise those links by storing US military equipment on their soil.

Rosen Plevneliev, the Bulgarian President, said it was too early to say if his country would join the Pentagon's initiative.

"At the current moment there is no proposal whatsoever to the Bulgarian government upon which we can start discussions," he said.