SEOUL — The United States is committed to defending South Korea from an attack by the North and would use nuclear forces if needed, Defense Secretary Donald H. Rumsfeld told the government here yesterday.

Mr. Rumsfeld, who finishes his first official visit to Asia today, said the U.S. commitment to South Korea includes "the continued provision of a nuclear umbrella" for South Korea, according to a statement issued after joint security talks.

"We understand that weakness can be provocative, that weakness can invite people into doing things that they otherwise might not even consider," Mr. Rumsfeld told a joint news conference with South Korean Defense Minister Cho Young-kil.
The two defense chiefs also discussed transferring some of the 37,000 U.S. troops in South Korea to two areas south of the demilitarized zone.

The tasks carried out by the U.S. forces will be handed over to South Korean troops, including security for the truce area of Panmunjom at the demilitarized zone separating the two Koreas and the development of South Korean antiartillery capabilities.

Mr. Rumsfeld met with South Korean President Roh Moo-hyun and told him that the United States would like Seoul to send "self-sufficient" troops to Iraq that do not need the protection of U.S. combat forces or help with supplies, said a senior defense official at the meeting.

South Korea has said it will send additional troops in the coming months but did not say whether they will be combat troops or humanitarian forces. The dispatch of humanitarian forces would require protection from terrorist attacks and Iraqi insurgents by U.S. or allied troops.

At the annual defense talks, the two sides agreed that North Korea poses a "global threat," the joint statement said.

Mr. Rumsfeld and Mr. Cho share the "grave concern that North Korea's self-acknowledged nuclear-weapons program threatens regional and global security and violates North Korea's commitment to a nuclear-free peninsula."

North Korea has not tested a nuclear device, but the CIA stated in a recent report to Congress that Pyongyang has "validated" atomic weapons design to the point of posing a credible nuclear threat.

North Korea is continuing to develop nuclear, chemical and biological weapons and long-range missiles, and poses a danger of exporting the weapons and technologies, the statement said.

The United States pulled out all of its tactical nuclear weapons, including nuclear land mines, in the early 1990s. It was then that Washington promised to use its nuclear forces, primarily missile-equipped submarines, to counter any atomic threats to South Korea.

However, the explicit restatement of that promise was unusual, and appeared intended to pressure North Korea in upcoming nuclear arms talks and to persuade South Korea not to develop its own atomic weapons.

North Korea's deployment of nuclear arms in the late 1990s shifted the strategic balance on the peninsula in Pyongyang's favor.

The United States' willingness to use nuclear arms to defend South Korea is expected to anger the communist North, which has accused the Bush administration of planning a nuclear attack.

Davy Crockett Nuclear Bazooka

Asked later about the nuclear assurances, Army Gen. Leon LaPorte, commander of U.S. forces in South Korea, said he could not comment on operational plans.

"Our concern is to maintain a nuclear-free Korean Peninsula," Gen. LaPorte said in an interview with reporters.

The United States is developing nuclear weapons capable of penetrating deep, rock-hardened bunkers like those housing North Korean weapons, U.S. officials have said.

Both leaders called on North Korea to "completely, verifiably and irreversibly dismantle its nuclear-weapons programs" and halt the testing, development, deployment and export of weapons of mass destruction, missiles and related technologies, the statement said.

North Korea should take the opportunity of the six-party talks to denuclearize, the statement said.

Assistant Secretary of State James A. Kelly is in Tokyo and will visit Seoul later this week. He told reporters that a resumption of six-party talks is expected as early as mid-December.

Mr. Rumsfeld said at the press conference that the 13-year plan to move forces away from the demilitarized zone and consolidate bases over the next several years will strengthen the 50-year-old alliance with South Korea.

The alliance is successful because "we have had the ability to deter and defend and, if necessary, prevail," Mr. Rumsfeld said. "And that has been well understood. I can assure you it will be well understood in the years ahead, and, needless to say, neither of our governments would do anything that would in any way weaken the deterrent and the capability to defend."

Mr. Rumsfeld and South Korean leaders did not discuss cutbacks in the numbers of troops, but a U.S. official quoted Mr. Roh as saying that weapons upgrades and organizational reform make the number of troops less important than in the past.
"It is not numbers of things, it is capability to impose lethal power, where needed, when needed, with the greatest flexibility and with the greatest agility," Mr. Rumsfeld said.

Defense officials have said they do not want U.S. military forces to be used as a vulnerable "tripwire" in any initial attack by North Korea's 1.2-million-troop army.
Thousands of U.S. Army forces are deployed in camps spread close to the demilitarized zone and would be quickly overrun by invading North Korean forces or forced to make a difficult withdrawal through the urbanized Seoul area during a conflict.

The two sides were unable to reach an agreement on the relocation of some 700 to 1,000 U.S. troops from the military's Yongsan garrison in Seoul. South Korea does not want the troops in the Seoul area to be moved. The U.S. wants them pulled back to areas around Osan air base, located south of the capital.