Robert Gates dropped into Iraq for a previously unnanounced visit this morning while travelling through the region on his Middle East tour.
Gates reportedly flew into Fallujah by helicopter, and headed straight into a meeting with US commanders.
Gates said in a speech in Tel Aviv that the carnage from car bombs in Baghdad on Wednesday would not deter Washington from its security plan.
"We have anticipated from the very beginning... that the insurgency and others would increase the violence to make the people of Iraq believe the plan is a failure," Gates said. "We intend to persist to show that it is not."
Before leaving Tel Aviv for Baghdad, Gates told reporters that he would like to see faster progress. "The Iraqis have to know... that this isn't an open-ended commitment," Gates said.