The general who oversees the war in Iraq and Afghanistan slumped at the witness table yesterday while testifying at a US Senate hearing.
General David Petraeus, 57, revived after a few seconds and left the room without assistance.
After about 20 minutes he returned to the hearing room but Senator Carl Levin, the panel chairman, decided to postpone the hearing.
A spokesman said the four-star general was thought to be dehydrated and jet-lagged.
General Petraeus had finished telling Senator John McCain that he believed the planned 2011 pullout of US troops from Afghanistan remained on track, and Mr McCain was responding when the room fell silent and aides began crowding around the general.
The general, who heads the US Central Command, briefly put his head on the table, then rose, appearing dazed.
He stood up with his own exertions and was escorted from the room.
General Petraeus returned to the room briefly and told the senators he "was feeling a little bit lightheaded there".
"It wasn't Senator McCain's question," the general told the Senate hearing, being held in a climate of increasing unease at the progress of the war in Afghanistan.