SEOUL (AFP) - US Secretary of Defense Donald Rumsfeld has suggested that South Korea take wartime control of its troops in the next three years, Yonhap news agency said quoting a military source.

Rumsfeld sent a letter to South Korean Defense Minister Yoon Kwang-Ung in mid-August, insisting it be "reasonable" to do the control transfer in 2009 -- three years earlier than wanted by Seoul, Yonhap said.

South Korea has preferred 2012 as a target year for the transfer, citing a need for more time to prepare for the major change in the five-decade alliance.

Under a mutual defense treaty, South Korean troops would come under the operational control of the commander of US forces in South Korea, who leads the combined forces command, during times of conflict.

The US wartime operational rights have been the backbone of bilateral security ties since 1950 when US troops deployed to the Korean peninsula to repel North Korean invaders from South Korea.

Some 32,500 US soldiers are stationed at present in Seoul to help 650,000 South Korean military troops face up to North Korea"s 1.2 million-strong army.

The United States and South Korea have held talks on readjusting their traditional military alliance amid increasing calls from South Korea to have independent control of its military.

The United States also plans to reduce its forces in South Korea to 25,000 by 2008 and is seeking flexibility to deploy them elsewhere in times of need.

In 2003 it agreed to hand over 10 major military missions to South Korean forces, including a patrol at the border truce village of Panmunjom.