On 12 February 2013, North Korean state media announced it had conducted an underground nuclear test, its third in seven years. A tremor that exhibited a nuclear bomb signature with an initial magnitude 4.9 was detected by the China Earthquake Networks Center, Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization and the United States Geological Survey. In response, Japan summoned an emergency United Nations meeting for 12 February and South Korea raised its military alert status. It is not known whether the explosion was nuclear, or a conventional explosion designed to mimic a nuclear blast; as of two days after the blast, Chinese, Japanese, and South Korean investigators had failed to detect any radiation.

North Korea conducted its fourth nuclear detonation on 6 January 2016 at 10:00:01 UTC+08:30. At the Punggye-ri Nuclear Test Site, approximately 50 kilometres northwest of Kilju City in Kilju County, an underground nuclear test was carried out. The United States Geological Survey reported a 5.1 magnitude earthquake from the location; the China Earthquake Networks Center reported the magnitude as 4.9.