For more than 50 years, the U.S. Army in South Korea has kept its headquarters at sprawling Yongsan Garrison, in the heart of Seoul. In July, the South Korean and U.S. governments announced that Yongsan would be closed by 2008, and the troops moved to Pyongtaek, 80 kilometers south of the capital.

The United States first considered giving up the Yongsan Garrison and moving its eight-thousand troops elsewhere in the late 1980s.

But there were problems. First, there was the question over how to pay for the move - estimated to cost up to $4 billion. South Korea is going to cover that.

Then there was the problem of finding a suitable new location in the small, mountainous country. Many cities were unwilling to accept a new base, because residents feared the presence of so many foreigners - especially rowdy young American troops - would be too disruptive. At the same time, some Seoul residents feared closing Yongsan would cost civilian jobs.

The plan stalled again in the early 1990s, when it was learned that North Korea was building nuclear weapons, and the peninsula faced the threat of war. Defense officials in both Seoul and Washington feared moving the troops might encourage the North into bolder military action.

Chun In-young, a specialist in security affairs at Seoul National University, says that after so many years of talking, most South Koreans understand the plan to move the troops to Pyongtaek, 80 kilometers south of Seoul.

"Many things have changed and happened over the last 10 years, so many Koreans now accept what's happening, although our views are divided over that issue," he said. "Some conservatives, so called, want them to stay for much longer, and the young generation want [them] to pull back from that area."

The United States is eager to make the move, but more profound changes are in the works. As Washington reorganizes its global forces to fight the war on terrorism, many military experts think fewer troops are needed in South Korea. At least 12,000 infantry soldiers will be moved permanently out of the country over the next few years - almost a third of the total U.S. force currently there.

U.S. troops have been in South Korea since the peninsula was divided in 1945, and the Americans fought alongside the South during the war against North Korea in the early 1950s. Communist North Korea and the democratic South are technically still at war: they have never signed a peace treaty, even though hostilities ended in 1953.

Robert Einhorn, a specialist on the Korean Peninsula with the Center for Strategic and International Studies in Washington, says the United States wants to update its force positioning around the world.

"Washington is asking itself whether the Cold War disposition of forces that existed for 50 years, whether that is appropriate," he said.

Some U.S. defense experts have argued that it makes military sense to move American troops south of Seoul. The South Korean capital is within range of thousands of North Korean cannons and rocket launchers. Should hostilities resume, troops in Seoul and farther north, near the Demilitarized Zone dividing the peninsula, could become trapped.

In theory, at least, troops based farther south will be able to rush north to defend Seoul.

However, there are concerns that closing Yongsan too quickly could raise doubts about U.S. resolve to defend South Korea. Mr. Einhorn of the Center for Strategic and International Studies says the United States should be flexible about the timing of the move.

"I think it's important that we pursue this in away that doesn't unsettle our South Korean allies," he said. "Their concern is that it will send the wrong signal to the North."

For many Seoul residents, closing Yongsan will be a sign of their country's strength and independence. Professor Chun notes that the Japanese military occupied the base in the first half of the 20th Century during the 45 years Japan ruled Korea. After Japan's defeat in World War II, U.S. troops moved in, leaving some Koreans with the sense that they were still under foreign control.

"It's become kind of a symbol of a U.S. superiority or, what can I say, arrogance," he said. "It's a part of Seoul, it's a big military base remaining there, and it should be one way or another re-arranged. That was the kind of sentiment of the Korean people."

But for other South Koreans, losing Yongsan will mean a big change in their lives. Thousands of Koreans work on the base, which covers nearly 300 hectares, or in the shops, restaurants and bars that cater to the troops and their families. Most of those businesses are clustered in an area of Seoul known as Itaewon.

Some business owners in Itaewon expect to close when Yongsan's gates shut in 2008, but others expect to survive by catering to the diplomats and thousands of other foreigners who live nearby. And new businesses might move in to cater to the crowds of tourists and Seoul residents expected to visit a new park that is scheduled to replace the old army barracks.