SEOUL, South Korea -- North Korea said Thursday it will immediately revive a Soviet-designed nuclear power plant the United States suspects was being used to develop nuclear weapons before it was frozen in 1994.
A dismayed South Korea urged its neighbor to reverse the decision. In Washington, a spokesman for President Bush called the situation "regrettable" but said the United States had no plans for military action in response to the North Korean decision.
With a bitter winter ahead, a North Korean Foreign Ministry spokesman said his country had no choice but to reactivate the reactor and resume construction of other nuclear facilities to supply desperately needed power after a U.S.-led decision last month to suspend annual oil shipments of 500,000 tons.
KCNA, the North's state-run news agency, quoted the spokesman but did not name him.
A South Korean government official said it would take about two months for North Korea to reactivate its old nuclear plant.
The North Korean announcement followed the seizure and release this week of a ship carrying North Korean Scud missiles to Yemen. North Korea's missile customers have also included Libya, Iran, Syria, Pakistan and Egypt.
It wasn't clear whether the interception influenced the decision, but an editorial in the North's official newspaper, Rodong Sinmun, said: "It is necessary to heighten vigilance against the U.S. strategy for world supremacy and 'anti-terrorism war.'"
In Washington, White House spokesman Ari Fleischer said the United States would continue to seek a peaceful resolution of the issue of North Korea's nuclear program.
"The announcement flies in the face of international consensus that the North Korea regime must fulfill all its commitments, in particular dismantling its nuclear weapons program," Fleischer said.
The U.N. nuclear agency, which has monitored North Korea's nuclear program since 1994, urged the country to "act with restraint." Mohamed ElBaradei, director-general of the International Atomic Energy Agency, said North Korea had asked his agency to remove seals and monitoring cameras from all its nuclear facilities. He urged them to allow the seals to remain in place and warned that tampering with them would be a violation of North Korea's agreement with the IAEA.
ElBaradei also asked North Korea to meet with U.N. technical experts to discuss ways of monitoring restarted reactors and related facilities to ensure they are used only for peaceful purposes.
The North Korean nuclear program was suspended under a 1994 deal with Washington, averting a possible war on the Korean Peninsula. Experts say North Korea could quickly extract enough plutonium from its old facilities to make several nuclear weapons.
Under the 1994 pact, North Korea agreed to freeze the plutonium program in return for two modern, light-water reactors built by a U.S.-led consortium and 500,000 tons of oil a year until the reactors are built.
Defense Secretary Donald H. Rumsfeld says he believes the North already has one or two nuclear weapons. Speaking to reporters Thursday in Doha, Qatar, Rumsfeld called North Korea "a very strange regime" but said it was not time to abandon diplomacy.
"I have no idea when any country, including the United States, would make the judgment that the diplomatic effort, which is under way, can't bear fruit," Rumsfeld said.
North Korea has often used the threat of confrontation as a means of gaining leverage ahead of negotiations, though it was not immediately clear whether its latest announcement was part of such a strategy.
It also has often complained about delays in construction of the reactors, which are several years behind schedule.
"If you carefully read the North's statement, its stance of wanting a peaceful solution to the dispute over U.S. fuel oil deliveries remains unchanged," said Prime Minister Junichiro Koizumi of Japan.
Isolated North Korea, which depends on outside food aid, has pursued a reconciliation process with South Korea as well as diplomatic ties with other countries. But it has repeatedly sparred with the Bush administration.
The North Korean official said North Korea was obliged to revive the program because of a U.S.-led decision last month to suspend annual oil shipments. The suspension was designed to pressure North Korea to give up a more recent nuclear program based on uranium enrichment.
Japan, South Korea and the European Union were also signatories to the 1994 deal and backed the suspension of oil shipments, but North Korea has focused its anger on the United States.
The foreign ministries of Germany and Russia issued statements saying they were concerned by the decision and urged North Korea to abide by its obligations.
"The prevailing situation compelled the (North Korean) government to lift its measure for nuclear freeze ... and immediately resume the operation and construction of its nuclear facilities to generate electricity," the North Korean spokesman was quoted as saying in comments monitored by South Korea's Yonhap news agency.
"Our country faced an immediate problem in electricity generation because the United States has virtually abandoned its obligations," the spokesman said.
"Our principled stand is that the nuclear crisis on the Korean Peninsula should be resolved peacefully. It's totally up to the United States whether we will freeze our nuclear facilities again."
The government of South Korean President Kim Dae-jung, who has sought to reconcile with North Korea, urged the North to abide by international nuclear nonproliferation accords.
"The government expresses deep regret and concern that the North Korean Foreign Ministry spokesman's statement could create tension on the Korean Peninsula," said Seok Dong-yun, a South Korean Foreign Ministry spokesman.
Chinese Foreign Ministry spokesman Liu Jianchao said China remained committed to a Korean Peninsula without any nuclear threat, but said China remained committed to helping its neighbor.
"China has given North Korea assistance in its difficulties. It will continue to do so," Liu said.
U.S. Deputy Secretary of State Richard Armitage, who was in China for talks, said Thursday that China shares American concern about North Korea's nuclear program and is expected to urge "different behavior" on its isolated, secretive ally.