SEOUL — 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 Pyongyang may be ready to conduct an atomic test at any time.

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 United States, South Korea, and other countries have urged the North to scrap its nuclear test plans or face grave consequences.