President Bush was rushed from the Oval Office to an underground bunker after a security alert on Wednesday.
Force to flee - President Bush
The scare came when it was reported that an unidentified aircraft had entered restricted Washington airspace.
As White House security plans swung into action Vice-President Dick Cheney was also moved to a secure location.
But all of the effort proved needless when it later transpired that the supposed aircraft was in fact nothing more than a blip on a radar screen.
Helicopters were scrambled to investigate the incident, as White House staff were cleared out of the West Wing and tourists in the East Wing were evacuated to a park across the road from the residence.
Heavily armed guards rushed to take up positions around the White House
Armed secret service agents took up positions all around the building's perimeter.
"There was a report or an indication that an aircraft had entered restricted airspace around the White House, and so there was some precautionary measures that were taken," White House press secretary Scott McClellan said.
The president remained in the bunker for a short time, until it became clear that there was in fact no aircraft.
It was the first time Mr Bush sought refuge in the bunker since night of the 11 September attacks in Washington and New York, more than three years ago, a White House spokesman said.