Camp Adder, one of just five U.S. bases now occupied by the 8,000 troops still in Iraq, will be the last to close, the Los Angeles Times reported Wednesday.
"We're quickly, quietly and professionally moving out," Army Lt. Col. Charles Krumwiede said.
Krumwiede said no U.S. troops will remain in Iraq secretly, despite suspicions voiced by some Iraqis.
"We're honoring the security agreement" reached in 2008 between the George W. Bush administration and the Iraqi government, he said.
A senior Pentagon official said 200 to 300 military trainers will remain on 10 Iraqi bases.
Fewer than 4,000 troops remain in Iraq and officials say they will likely be out in the next few days, Voice of America said.
One general overseeing the drawdown, Army Brig. Gen. Jonathan Ives, said the trucking operation in Iraq was the largest since the World War II mission that supplied U.S. troops invading Europe.
"We've moved a million tons with 4,000 vehicles in the same amount of time [as the World War II operation]. They did it over 90 days, a three-month period. We've done it really from Oct. 16 to [Wednesday]," he told VOA.
Equipment too worn or too expensive to ship out is being left for the Iraqis, the Times said. Krumwiede said the military gear being left at Camp Adder was worth about $220 million, but would cost about $300 million to ship back.
The military will save $700 million by leaving some equipment in Iraq, said Maj. Gen. Jeffrey S. Buchanan, spokesman for U.S. forces in Iraq.
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