SEOUL, South Korea — North Korean leader Kim Jong Un issued "important" guidelines on how to bolster the army and protect the nation's sovereignty at a high-level ruling Workers' Party meeting, state media said Sunday, an indication that Pyongyang may be ready to conduct an atomic test anytime.

North Korea said last month that it would conduct its third nuclear test to protest international sanctions toughened over its long-range rocket launch in December. The U.S., South Korea and other countries have urged the North to scrap its nuclear test plans or face grave consequences.

North Korea says U.S. hostility and the threat of American troops in South Korea are important reasons behind its nuclear drive. The country also says it has the sovereign right to launch rockets to send satellites into orbit under a space development program; the U.S. says the December launch 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 long-range rocket launches.

Recent satellite photos showed North Korea may have been sealing the tunnel into a mountainside where a nuclear device would be exploded.

Kim convened a meeting of the Workers' Party's Central Military Commission and made a "historic" and "important concluding speech" that serves as a guideline for strengthening the military and defending national security and sovereignty, the official Korean Central News Agency said. It did not say when the meeting took place.

Top party and military leaders who attended the meeting "evinced their firm determination to unconditionally and thoroughly implement the militant tasks set forth by him," KCNA said.

Analyst Hong Hyun-ik at the private Sejong Institute in South Korea said he believes Kim's guidelines refer to a nuclear test and suggest that North Korea appears to have completed formal procedural steps and be preparing to conduct a nuclear test soon.

By publicizing the Workers' Party meeting, North Korea also aims to "employ pressure on the West and unite its people" behind Kim, Hong said. Kim took power after the December 2011 death of his father, Kim Jong Il.

U.S. and South Korean troops are to conduct naval drills involving a nuclear-powered American submarine off the east coast of the Korean Peninsula this week. South Korean military officials said the maneuvers are part of regular joint military training that the allies had scheduled before the latest nuclear tensions began. But they still could be used as a show of force against North Korea.

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 U.S. conducted other drills, but the allies have repeatedly said they have no intention of attacking the North.

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