"We have moved troops off of the DMZ, where frankly, they were performing nothing except, a kind of useless -- and indeed I would say counterproductive -- tripwire function," Wolfowitz said.

South Korea is seeking assurances that the 4,000 troops will return once their Iraq mission is concluded and has vigorously opposed any reduction in US troops, finding comfort that the presence of US troops in the region virtually guarantees immediate US military involvement if North Korea were to invade the South.

Wolfowitz told members of the Senate Foreign Relations Committee Tuesday that changes were already in the works, reflecting that "we have already made some adjustments to our posture in Korea."

The decision to remove troops defending South Korea underscores strains that have been placed on the US Army as it fights insurgents in Iraq.

Wolfowitz testified that plans to withdraw troops from South Korea and redeploy them in Iraq are part of a global realignment of US forces that has been under consideration for months.

"We had planned on some reductions. We need an extra brigade in Iraq, and in fact the brigade in Korea is ideally suited for that," he told the Senate Foreign Relations Committee.

"We had been discussing for some time with our Asian colleagues, with the Congress, the whole restructuring of the US global footprint," Wolfowitz told the panel, at a hearing on Iraq reconstruction.

"It was concluded over a year ago, that it was long overdue to reduce the strain on our army that comes from having these continuous one-year unaccompanied tours in Korea," Wolfowitz said.

At the same hearing, Lieutenant General Walter Sharp, director for strategic plans and policy for the Joint Chiefs of Staff, testified that troops relocated to Iraq will serve for between one and two years.

"It will be a 12-month commitment." he said.

"We rotate troops into Korea on a continuous basis, so about half of them will have been in Korea already six months," he said.

"Some of the tours will be short -- will be 12 months -- others will go up to a maximum of 23 months," said Sharp.

Washington announced Monday that it has notified South Korea and Japan it would withdraw some 3,600 US troops from South Korea for up to a year's combat duty in Iraq -- the first reduction in US force levels on the Korean peninsula since the early 1990s.

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