South Korea lost track of a missile fired during last week’s drills held in response to a North Korean intermediate-range ballistic missile (IRBM) launch, Seoul officials said on Thursday, in a failure that raised questions over the missile’s performance.

North Korean leader Kim Jong-un oversaw a tactical nuclear exercise to assess his country’s "war deterrent and nuclear counterattack capability" in response to recent joint military training by South Korea and the United States, Pyongyang's state media said on Monday.