"Let the people of Iraq vote if they want the US to stay or leave"
Bob Kaye, Bohemia, US
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He contrasted the US position in South Korea, where US troops have been present since the end of the 1950-53 Korean war, with its withdrawal from Vietnam where it "just left lock, stock and barrel".
"The idea is more a model of a mutually agreed arrangement," he said. "The Korea model is one, the security relationship we have with Japan is another."
Gates also said US military commanders should not feel constrained by political pressure in Washington to make a decision in September on whether to begin reducing US troop levels in Iraq.
Earlier, Lieutenant-General Raymond Odierno, the number two US commander in Iraq, told reporters that he may not be able to make a full assessment by September of whether the current buildup of US troops in Iraq is stabilising the country.
"We've made small progress here. We have not made the progress that I think is necessary yet"
Raymond Odierno, senior US commander in Iraq
"We've made small progress here. We have not made the progress that I think is necessary yet, but I hope over the summer that we will continue to make progress," Odierno said.
"Right now if you asked me, I would tell you I'll probably need a little bit more time to do a true assessment."
George Bush, the US president, has also alluded to the strategy shift Gates is considering, talking about a "Plan B-H" that would incorporate recommendations from the Baker-Hamilton Commission.
Last year, a group headed by James Baker, a former secretary of state, and Lee Hamilton, a former representative, proposed a phased reduction of US forces with a small force left in Iraq to protect the country's borders and fight al-Qaeda.
Currently, there are about 147,000 US soldiers in Iraq, but the total is expected to rise to about 160,000 over the coming months.