S Korea, US in drills amid nuclear threat SOUTH Korean and US forces are conducting drills in a show of force partly directed at North Korea amid signs that Pyongyang will soon carry out a threat to conduct its third atomic test. The region is also seeing a boost in diplomatic activity focused on North Korea's announcement last month that it will conduct a nuclear test to protest UN Security Council sanctions toughened after a December satellite launch that the US and others say was a disguised test of banned missile technology. Pyongyang's two previous nuclear tests, in 2006 and 2009, 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, Defence 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. On Monday, South Korean and US militaries kicked off three-day exercises off the Korean Peninsula's east coast that involve live-fire exercises, naval manoeuvres and submarine detection drills. South Korea's Joint Chiefs of Staff said the manoeuvres 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. North Korean state media on Saturday described the drills as a joint exercise for a pre-emptive attack on the country. North Korea has said similar things when South Korea and the US conducted other drills; the allies have repeatedly said they have no intention of attacking the North. North Korea says US hostility and the threat of American troops in South Korea are important reasons behind its nuclear drive. The US 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. Diplomats are meeting to find ways to persuade North Korea to scrap its nuclear test plans. New US 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 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.