The US and South Korea have agreed to speed up talks on giving Seoul greater control over its armed forces, which operate in joint command with the US.
The two sides said they would speed up discussions on "command relations and wartime... control".
Currently, a US general would command the joint forces in any future conflict, with North Korea for example.
Many South Koreans see regaining the wartime operational control of their military as an issue of national pride.
The control of troops issue dates back to the Korean war, when South Korea put the operational control of its forces under the US-led UN command.
South Korea took back the peace-time control of its troops in 1994, but the wartime control is still in the hands of the most senior US general in the country.
Earlier this month, South Korean President Roh Moo-Hyun said he wanted more control over South Korean forces in wartime.
A BBC correspondent says the alliance is coming under increasing strain, but that Seoul says it is still committed to a strong relationship with the US.
Shifting roleThe announcement came in a joint statement issued by US defence secretary Donald Rumsfeld and his South Korean counterpart, Yoon Kwang-ung, after they held an annual defence meeting on Friday.
It did not say when the talks would begin, or how soon South Korea might be ready to assume wartime control.
Mr Rumsfeld, who also met President Roh, said he welcomed South Korea's efforts to "take on more responsibility".
"Today, we see the relationship between our two countries evolving," he said.
But Mr Rumsfeld and other US officials played down the chances of the US giving up control soon.
Mr Rumsfeld and Mr Yoon also discussed North Korea, and said they hoped the military threat from Pyongyang would diminish as a result of six-party talks on its nuclear programme.
However, they said they were concerned about the North's "continued development of weapons of mass destruction and long-range missiles, along with the danger of proliferation of those weapons, and technologies".
The BBC's Charles Scanlon in Seoul says there have been tensions over how best to deal with the nuclear threat from the North.
Polls suggest that many South Koreans see the US as a bigger threat to peace than the North.
The US is also restructuring its troop presence in Asia, as part of a plan to become more agile, and intends to withdraw a third of its troops from South Korea by the end of 2008.
The US, which has had a military presence in South Korea since the end of World War II, currently has about 37,000 troops in the country, to complement the South's own force of 690,000.
