A tremor that exhibited a nuclear bomb signature with an initial magnitude 4.9 (later revised to 5.1) was detected by the China Earthquake Networks Center,[9] Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization[10] and the United States Geological Survey.

[1] In response, Japan summoned an emergency United Nations meeting for 12 February and South Korea raised its military alert status.

[12] On 12 February 2013, a spokesman for North Korea's army command said it had successfully conducted a third underground nuclear weapons test, according to the Yonhap.

[15] Before North Korea announced they had conducted the test, seismic activity had already been detected in North Korea by the United States Geological Survey (USGS) and the seismic network operated by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) Preparatory Commission, near the site of previous nuclear tests at Mantapsan in Kilju County.

The USGS upgraded the magnitude of the possibly nuclear tremor from 4.9 to 5.1, located 24 kilometres (15 mi) east-northeast of Sungjibaegam, North Korea.

[17] A citizen of Hyesan, Ryanggang Province of North Korea, 80 km (50 mi) west from the nuclear test site, reported that many 5- and 7-floor buildings shook very severely, and this caused cracking.

[36] On 17 December 2013, a member of South Korea's parliamentary intelligence committee said that a nuclear and missile test would occur soon to draw attention away from the execution of Jang Sung-taek.

[39] On 6 January 2016 North Korea says it has successfully carried out a hydrogen bomb test, which if confirmed, would have been a first for the country and a significant advancement for its nuclear program.

[42] Tibor Toth, executive secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization Preparatory Commission (CTBTO), confirmed the event's location was "roughly congruent with" nuclear tests carried out by North Korea in 2006 and 2009.