The Bush administration has decided to remove all U.S. nuclear weapons from South Korea, paving the way for a renewed demand that North Korea abandon its nuclear weapons program to ensure the strategic peninsula remains nuclear-free.

Administration officials said the decision was made last week after renewed consultations with South Korean authorities. President Bush was reported to have been reluctant to order removal of all U.S. nuclear weapons until he was confident that civilian and military leaders in Seoul would not interpret this as undercutting South Korea's security or the U.S. commitment to it.

Bush announced Sept. 27 that he had ordered withdrawal of all U.S. land- and sea-based tactical nuclear weapons, a move which required removal of U.S. nuclear artillery shells deployed in South Korea. However, air-delivered nuclear weapons, which are deployed at a U.S. base of F-16 aircraft in South Korea, were excluded from the Bush announcement. The initial indications here and in Seoul were that these weapons would be retained, at least for the time being.

An administration official said that Undersecretary of Defense Paul Wolfowitz had secretly informed Kim Jong Whie, national security adviser to South Korean President Roh Tae Woo, of Bush's intention to make dramatic cuts in nuclear weapons before Bush and Roh met in New York Sept. 23. Wolfowitz left open the issue of the air-delivered weapons, the official said, in order to test reaction on the Korean side.

Participants in the Bush-Roh meeting said the weapons cuts announced by Bush four days later were not discussed in the meeting, giving rise to a widespread belief that South Korea had been informed only at the last minute.

Only a few people knew of the Wolfowitz-Kim conversation that had preceded the meeting of the two presidents, administration sources said.

No timetable has been set yet for removal of the last of the U.S. nuclear weapons. The schedules will be set by commanders in the field, Washington sources said.

U.S. nuclear weapons have been in South Korea since the 1960s, at times in great numbers. In the early 1970s, some were deployed so close to the front line between South and North Korea that a congressional committee complained of the danger they might be overrun in an attack.

According to the Natural Resources Defense Council, the number of U.S. nuclear weapons in South Korea peaked at about 680 in the 1970s and declined to about 150 by 1981, the start of the Ronald Reagan administration. Robert S. Morris of the NRDC recently estimated that about 40 nuclear artillery shells and 60 nuclear bombs for aircraft delivery remain on South Korean soil.

An administration official said changes in military technology, including the increased effectiveness of high-tech conventional weapons used by U.S. forces this year in the Persian Gulf War, makes the presence of nuclear weapons on Korean soil much less important.

He said consideration is being given to supplying more such conventional weapons to U.S. and South Korean forces, and also to supplying Patriot anti-missile defense systems or other means of countering the longer-range ballistic missiles being deployed by North Korea.

North Korea's nuclear program is believed to include a small Soviet-supplied nuclear research reactor, a larger research reactor capable of providing significant quantities of plutonium and a nearby reprocessing plant that produces larger quantities of plutonium, the raw material for nuclear weapons.

Although North Korea signed the Nuclear Non-Proliferation Treaty in 1985, it has refused to agree to the international inspections of its nuclear facilities required under the treaty. Its most recent position is that it will not permit such inspections until all U.S. nuclear weapons have been removed from South Korea.

The elimination of U.S. nuclear weapons from South Korea will permit the United States, Japan and other nations to increase pressure on North Korea to stop its nuclear weapons program, which is generally considered the most dangerous security problem in East Asia and which is capable of producing sufficient plutonium for an atomic weapon within "a year or two," according to latest U.S. estimates.

Removal of the U.S. weapons also will permit Seoul to call for denuclearization of the peninsula, a goal that has considerable popular appeal on both sides of the North-South dividing line.