Tensions rise on Korean peninsula

South Korea placed more soldiers at frontier guard posts and told its fishermen to refrain from sailing near North Korean waters on Sunday, a day after the North Korean military declared an "all-out confrontational posture" against the South and threatened a naval clash. The North Korean threat on Saturday came in the same day when an American scholar said North Korean officials told him that they had "weaponized" enough plutonium for roughly four or five nuclear bombs. Also Saturday, North Korea's Foreign Ministry said the country would maintain its "status as a nuclear weapons state" as long as it perceived a nuclear threat from the United States.American intelligence officials have previously estimated that the North had harvested enough fuel for six or more bombs, although it has never been clear whether the North constructed the weapons. The scholar, Selig S. Harrison, said the officials had not defined what "weaponized" meant, but the implication was that they had built nuclear arms. The North conducted a test of a nuclear device in 2006, but it appeared to result in a fizzle and experts concluded the explosion was relatively small. While the country has often claimed to possess a "deterrent," this appears to be the first time it has quantified how much plutonium it says it has turned into weapons. After the threats on Saturday, South Korea ordered its military to heighten vigilance along the heavily fortified border with North Korea, according to a spokesman for the South Korean military joint chiefs of staff. North Korea's saber-rattling toward the South has increased in intensity since President Lee Myung-bak took office in Seoul a year ago with a vow to take a tougher stance on North Korea, reversing 10 years of his liberal predecessors' efforts to engage the North with economic aid. But what made the threat on Saturday unusual, and more worrisome to some South Korean analysts, was the way it was delivered: in a statement read on North Korean television by a uniformed spokesman for the North's joint chiefs of staff. "Strong military measures will follow from our revolutionary armed force," the spokesman, a colonel, said, according to Yonhap, South Korea's national news agency, which monitors North Korean broadcasts. Usually the North Korean government issues written statements that are delivered by the state-controlled media; sometimes the statements are read by press officers, not by a uniformed member of the military. The spokesman warned of a clash along a disputed western sea border between the Koreas. Their navies fought skirmishes there in 1999 and 2002. On Sunday, North Korea's state-run television and radio were repeatedly broadcasting the statement. They also reported that North Korean workers were whole-heatedly supporting their government, "swelling with hostility" toward Mr. Lee. After the threats on Saturday, South Korea ordered its military to heighten vigilance along the heavily fortified border with North Korea. Officers along the border were ordered to be on standby at their posts, according to a spokesman of the South Korean military joint chiefs of staff. "We are sending in more soldiers on guard post duty along the border," he said on Sunday. "But so far, we haven't seen any unusual movement from the North Korean military, and our measures do not include redeploying rear-area troops to the border." Lee Yong Sun, a fisherman in Baengnyeong, a South Korean island near the western maritime border, said Sunday that the marines there told all fishermen not to sail near the disputed border. It is always difficult to decipher the messages that North Korea's government is trying to send with its often bombastic statements. In times of crucial bargaining, North Korea often tries to drive a wedge between Washington and South Korea and raises the stakes by increasing demands and issuing threats. With President-elect Barack Obama about to take office and negotiations over the North's nuclear program expected to resume, it is possible that the North is merely setting up its negotiating position. But analysts said the North's remarks could also be an indication that it was intending to hold onto its arms despite an agreement it signed with five countries including the United States in 2005, in which it committed to eventually giving up any nuclear weapons. The exact conditions under which it would do so were left vague. Questions over the health of the country's leader, Kim Jong-il, also complicate any attempts to understand North Korea's aims. In August, there were reports that Mr. Kim suffered a stroke, and since then rumors have swirled about whether he is still making important decisions. Mr. Harrison, the scholar, presented North Korea's claims of weaponization on Saturday in Beijing after returning from North Korea's capital, Pyongyang. Mr. Harrison, a former journalist who is the director of the Asia program at the Center for International Policy, has traveled several times to North Korea to meet with senior officials there. "They've raised the bar and said, 'We are a nuclear weapons state, and deal with us on that basis,'–Mr. Harrison said at a news conference in the St. Regis Hotel. Mr. Harrison acknowledged that North Korea could be bluffing to use the claim of having nuclear weapons as a negotiating tactic. North Korea had declared to the United States last year that it possessed 37 kilograms of plutonium; officials told Mr. Harrison on his trip that they had weaponized almost 31 kilograms. Despite that news, he said all the officials he met with seemed eager to open discussions with the incoming Obama administration. "All the statements about Obama were very helpful, very respectful," he said. Mr. Harrison said the North Korean officials had several proposals for Mr. Obama, including allowing North Korea to have access to long-term, low-interest credit to buy food. South Korea had no immediate reaction to Mr. Harrison's report. Earlier Saturday, North Korea had appeared to toughen its stance toward Washington, saying that reopening diplomatic ties would not be enough to persuade it to give up its nuclear weapons. It said it would maintain its "status as a nuclear weapons state" as long as there was a nuclear threat from the United States. "We can live without normalizing ties with the United States, but we cannot live without a nuclear deterrent," a spokesman for North Korea's Foreign Ministry told its official news agency, KCNA. In the past, the North had said it would not dismantle any weapons until the United States changed what it termed its "hostile attitude." In the spokesman's comments, and his similar statement last Tuesday, North Korea laid out its demands as it prepared for a new series of negotiations with Mr. Obama, who will be inaugurated on Tuesday. In its Tuesday statement, North Korea indicated that the removal of an American nuclear threat meant the removal of South Korea from the American nuclear umbrella, the introduction of a verification mechanism to ensure that no American atomic weapons are deployed in or pass through South Korea, and even simultaneous nuclear disarmament talks among "all nuclear states," including itself. Six-nation talks on ending North Korea's nuclear programs, which include the United States, stalled in the last months of the Bush administration as the United States and North Korea bickered over how much nuclear inspection the North should accept.