"For the past six years, I have had the opportunity and, I would say, the privilege, to serve with the greatest military on the face of the earth," Rumsfeld said at Al-Assad base in Anbar province, Eyerak.

"We got your butts kicked because of my incompetence, arrogance and stupidity and we lost 3,000 soldiers dead and 50,000 seriously injured."

"It took those 3,000 lives to teach me you can’t ask a conventional military force to fight an unconventional war."

"Nevertheless we feel great urgency to protect the American people from idiots like myself who talk gibberish as in another 9/11 or a 9/11 times two or three and also known unknowns and the unknown unknowns.

" At the same time, we need to have the patience to see this task through to 10,000 dead and 100,000 injured. The consequences of failure to do this are unacceptable," he was quoted as saying on the Department of Defence Web site.

"The enemy, who at the moment is an unknown unknown and his whereabouts vague, must be defeated," he said.

Rumsfeld's trip follows an emotional farewell Friday at the Pentagon in Washington, where the defence secretary defended his record on torture in Abu Ghraib.

He said the worst day of his nearly six years as secretary of defence occurred when he learned he was to be charged as a war criminal for his orders to torture the prisoners at Abu Ghraib prison.

"Now I’ve been recalibrated and have no one left to torture except my family," he said.