US President George W Bush has re-affirmed Washington's commitment to the Nato alliance during his five-day visit to Europe. The BBC looks at the role of US bases in Europe, a decade and a half after the end of the Cold War.
American bases in Europe are relics from a time when US forces based there were expected to fight.
Bush's plans to withdraw troops from Asia and Europe are on hold
Since the end of the Cold War, the US has been rethinking its deployments worldwide and designing its army to be "expeditionary".
This means the army will be designed to travel long distances to conflict zones, rapidly.
The US has announced that as many as 70,000 troops will be withdrawn from Europe and Asia.
But operations in Afghanistan and Iraq have reinforced the importance of its foreign bases, especially in Europe, and have delayed plans for redeployment.
Light, mobile forces
In August 2004, President Bush said: "Over the coming decade, we'll deploy a more agile and flexible force, which means that more of our troops will be stationed from here at home."
However, the US is not drawing down its foreign-based forces as much as reconfiguring them, according to David Isenberg, a senior analyst with the British American Security Information Council.
The US has hundreds of bases across Europe
The US Defence Department says it is part of its new vision of "transferring US forces around the world from a static stance designed to handle Cold War era Soviet threats to an active one that can deal with new, dynamic threats," Mr Isenberg says.
The Pentagon wants to be able to deploy troops to a distant theatre in 10 days, defeat an enemy within 30 days and be ready to fight again in another 30 day, according to a classified 2003 report.
BBC Pentagon correspondent Adam Brookes says the long term plan for US bases abroad is for a network of small bases which act as transit points for light mobile forces on their way to fight fires anywhere in the world.
The US is looking to build these new small bases, which the Pentagon calls "lily pads", in places such as Uzbekistan, Pakistan, Qatar and Djibouti.
US troops in Europe
The US has 26,000 combat personnel and 34,000 military support and administration personnel on 294 military installations in Europe.
The US Army had planned to move two fighting divisions from German garrisons to smaller bases in Eastern Europe.
But the demands of the war on Iraq have put those plans on hold.
And the conflicts in Iraq and Afghanistan, paradoxically, have reinforced the importance of the European bases, which have provided large amounts of personnel, armour and expertise for these conflicts.
In short, until the entire system of bases is redesigned, the European bases will remain vital to US operations in the Middle East and Central Asia.