Speeding off in his motorcade after a meeting at the Nato summit hall, the leader of the world's only superpower left behind the critical briefcase that contains America's nuclear bomb codes.

"Rather than wait for everyone to gather he just took off", said White House spokesman Joe Lockhart.

The case contains the electronic launch codes needed for a US nuclear strike and provides a link with the Pentagon through a telephone.

It is carried by and chained to a military aide and supposed to be near the president whenever he is away from the White House.

When President Clinton's motorcade left without him the aide who carries the briefcase then had to walk the half-mile back to the White House from the Reagan building where the summit was being held.

"We're safe," remarked Mr Lockhart following the safe arrival of the aide, adding: "These things happen."

Fumbled football

It has been called the most dangerous handbag in the world.

The black attache case which has become known as the "nuclear football" has been passed from president to president since the days of Dwight Eisenhower.

Aides have been quick to dismiss this incident, but other presidents have had similar scares.

Other incidents include:

• Left on board Air Force One in Paris when Gerald Ford arrived at economic summit
  
• Jimmy Carter left codes in his suit when it was sent to the dry cleaners
  
• Separated from Ronald Reagan when he was shot in 1981