SEOUL, South Korea (AP) — South Korean and U.S. troops began naval drills Monday in a show of force partly directed at North Korea amid signs that Pyongyang will soon follow through on a threat to conduct its third atomic test.
The region has also seen a boost in diplomatic activity since last month, when North Korea announced it would conduct a nuclear test to protest U.N. Security Council sanctions toughened after a satellite launch in December that the U.S. and others say was a disguised test of banned missile technology.
Pyongyang's two previous nuclear tests, in 2006 and 2009, both occurred after it was slapped with increased sanctions for similar rocket launches. As it issued its most recent punishment, the Security Council ordered North Korea to refrain from a nuclear test or face "significant action."
North Korea's state media said Sunday that at a high-level Workers' Party meeting, leader Kim Jong Un issued "important" guidelines meant to bolster the army and protect national sovereignty. North Korea didn't elaborate, but Kim's guidelines likely refer to a nuclear test and suggest that Pyongyang appears to have completed formal procedural steps and is preparing to conduct a nuclear test soon, according to South Korean analyst Hong Hyun-ik.
"We assess that North Korea has almost finished preparations for conducting a nuclear test anytime and all that's left is North Korea making a political decision" to do so, South Korean Defense Ministry spokesman Kim Min-seok told reporters Monday.
The spokesman said he couldn't disclose further details because they would involve confidential intelligence affairs. Recent satellite photos showed North Korea may have been sealing the tunnel into a mountainside where a nuclear device could be exploded.
A North Korean nuclear test "seems to be imminent," South Korea's U.N. Ambassador Kim Sook said Monday at a news conference at U.N. headquarters in New York.
He said there are "very busy activities" taking place at North Korea's nuclear test site "and everybody's watching." The ambassador said he expects the Security Council to respond with "firm and strong measures" in the event of a nuclear test.
On Monday, the South Korean and U.S. militaries kicked off three days of exercises off the Korean Peninsula's east coast that involve live-fire exercises, naval maneuvers and submarine detection drills.
South Korea's Joint Chiefs of Staff said the maneuvers are part of regular joint military training that the allies had scheduled before the latest nuclear tensions began. But the training, which involves a nuclear-powered American submarine, could still send a warning against possible North Korean provocation, a South Korean military official said, requesting anonymity because of department rules.
Later Monday, Pyongyang's state media said the drills showed that the U.S. and South Korea have been plotting to attack North Korea and increased the danger of a war on the divided peninsula.
"The dark cloud of war is approaching to the Korean Peninsula," North Korea's official Uriminzokkiri website said in a commentary. "Our patience has the limit."
North Korea said similar things when South Korea and the U.S. conducted previous drills; the allies have repeatedly said they have no intention of attacking the North.
North Korea says U.S. hostility and the threat of American troops in South Korea are important reasons behind its nuclear drive. The U.S. stations about 28,500 troops in South Korea, a legacy of the 1950-53 Korean War, which ended with an armistice, not a peace treaty.
North Korea also has denounced sanctions over its rocket launches, saying it has the sovereign right to launch rockets to send satellites into orbit under a space development program.
North Korea's two previous nuclear tests are believed to have been explosions of plutonium devices, but experts say the North may use highly enriched uranium for its upcoming test. That is a worry to Washington and others because North Korea has plenty of uranium ore, and because uranium enrichment facilities are easier to hide than plutonium facilities are.
Diplomats are meeting to find ways to persuade North Korea to scrap its nuclear test plans. New U.S. Secretary of State John Kerry and his South Korean counterpart Kim Sung-hwan held a telephone conversation Sunday night and agreed to sternly deal with any possible nuclear provocation by North Korea, Seoul's Foreign Ministry said in a statement.
The chief nuclear envoys of South Korea and China met in Beijing on Monday and agreed that they would closely coordinate on ways to stop North Korea from conducting a nuclear test, according to Seoul's Foreign Ministry. China is North Korea's main ally and aid benefactor.
China has refused to say whether it was sending an envoy to North Korea or whether Pyongyang has informed Beijing about its plans for a nuclear test. China's Foreign Ministry on Monday reiterated Beijing's opposition to a test, though it did not mention North Korea by name.
"We call on all sides, under the current circumstances, to avoid taking measures which will heighten regional tensions. We hope all parties concerned can focus their efforts more on helping to ease tensions on the peninsula and throughout the region and jointly maintain peace and stability on the peninsula," Chinese Foreign Ministry spokeswoman Hua Chunying said at a daily media briefing in Beijing.
Associated Press researcher Zhao Liang in Beijing and AP writer Edith M. Lederer at the United Nations contributed to this report.