A June 8 article about proposed U.S. troop reductions in South Korea incorrectly stated that the removal of about 12,000 troops would be the largest from the Korean Peninsula in nearly in half a century. The United States withdrew 20,000 of about 64,000 troops from South Korea in 1971. (Published 6/10/04)

The United States plans to withdraw a third of its 37,000 troops stationed in South Korea before the end of next year as part of the most significant realignment of U.S. forces on the Korean Peninsula in half a century, South Korean officials said Monday.

The withdrawal underscores a broader move by the Pentagon to transform troops stationed at traditional, fixed bases into more mobile forces for rapid global deployments. Defense officials also have proposed pulling two armored Army divisions out of Germany and repositioning some fighter aircraft and Navy command staff in Europe to make it easier to deploy forces to the Middle East, Central Asia and other potential hot spots.

In the case of South Korea, the planned move would mark the largest U.S. troop withdrawal from the peninsula since the Korean War, while shifting a greater burden of defense to the South Koreans themselves. A U.S. delegation, led by Assistant Secretary of Defense Richard Lawless, informed the South Koreans Sunday night of the Pentagon's intention to withdraw the troops, South Korean officials said.

The Pentagon has already announced plans to redeploy 3,600 troops this summer from South Korea to Iraq. The new proposal greatly expands the number of troops to be withdrawn -- involving about 12,500 by December 2005, Kim Sook, head of the Foreign Ministry's North America bureau, told reporters in Seoul on Monday.

It was not immediately clear which U.S. forces would be going -- or where. A senior U.S. military officer familiar with the planning, who spoke on condition of anonymity, said in an interview that many such details have yet to be worked out.

"Much of the planning has involved thinking in terms what military capabilities will still be needed in Korea, not the specific soldiers or units," the officer said.

Moreover, the pullout from Korea could end up being largely offset by a buildup of U.S. forces elsewhere in the Pacific -- notably in Guam, where Pentagon officials envision stationing more aircraft and submarines, and in Hawaii, where an aircraft carrier may be relocated from the mainland United States.

The withdrawal would be the first major troop cut on the Korean Peninsula since the early 1990s, when 7,000 U.S. troops were taken out. Kim said officials at the South Korean National Security Council, Defense Ministry and Foreign Ministry would review the proposal before giving a response. "We'll formulate a position and then notify the United States," he told reporters in Seoul.

The U.S. decision sparked divergent reactions in South Korea. Members of President Roh Moo Hyun's allied Uri Party indicated they would not protest the decision, but legislators from the more conservative opposition Grand National Party, which has accused Roh of warming to North Korea while alienating the United States, expressed dismay.

"In a situation where the nuclear issue in the North and Pyongyang's conventional weapons capabilities still loom as a threat to our security, the drastic reduction of troops would only harm the security of the Korean Peninsula," GNP legislator Park Jin told South Korea's JoongAng Ilbo newspaper. South Korea's semi-official Yonhap news agency quoted an unnamed South Korean official as saying the government in Seoul was advocating a more gradual pullout of the forces by 2013.

The U.S. proposal comes as U.S. relations with the South Korean government are being tested by South Korea's policy of rapprochement with the communist government of North Korean leader Kim Jong Il despite its threats to become a renegade nuclear power. Military officials in Seoul and Pyongyang recently agreed in landmark talks to adopt a standard radio frequency and signaling system for their navies and to exchange data on illegal fishing. They also decided to set up a hotline between the two sides.

The United States has kept troops in South Korea since the Korean War, in part to help repulse a potential invasion from the North.

The South Koreans have said they are now seeking more independence -- although clearly, they are trying to strike a balance, attempting not to distance themselves too much from the United States.

Roh, who recently won a majority in parliament, has insisted that South Koreans should shoulder a greater role in national defense, but this weekend he pledged that his government would continue to "properly nurture the South Korea-U.S. alliance."

Although the number of U.S. troops in South Korea will drop, the U.S. government has insisted it will not weaken defense capabilities against the North, which maintains a 1.1 million-member standing army, possesses ballistic missiles and perhaps six to eight nuclear devices, according to U.S. intelligence reports.

Speaking at an Asian security conference in Singapore last week, Defense Secretary Donald H. Rumsfeld, the principal author of the plan for a mobile force, said the United States would be making fundamental changes in its troop presence on the Korean Peninsula as well as in Europe.

Proponents of the re-basing plan argue that current overseas concentrations of U.S. forces still largely reflect Cold War calculations, not 21st-century concerns about potential conflicts in the Middle East, the Caucasus and elsewhere. They say it would be more efficient to withdraw from South Korea and Germany and establish skeletal new bases in Eastern Europe and the Central Asian republics that could serve as staging areas in the event of crises.

But some U.S. defense experts and Asian and European officials worry that reducing the U.S. military presence could undercut U.S. influence abroad and prove less advantageous than anticipated. A study published last month by the Congressional Budget Office noted that any major moves from overseas locations would require significant spending to provide basing someplace else. It estimated that while annual savings could exceed $1 billion, the net up-front investment to resettle U.S. troops "would be substantial -- on the order of $7 billion."

Further, the study concluded that the restationing of Army forces "would produce at best only small improvements in the United States' ability to respond to far-flung conflicts." To deploy troops "from the likely locations of new bases would not be significantly faster than deploying them from current bases," the study said.

Graham reported from Washington. Special correspondent Joohee Cho contributed to this report.

U.S. soldiers participated in exercises near Seoul last month. Their numbers would drop by 12,500 under a new plan.