[8] North Korea's previous nuclear test was conducted 8 months earlier in January 2016 and drew sharp international condemnations.

According to South Korean and Japanese estimates, the nuclear yield was equivalent to about 10 kilotons of TNT (10 kt), generating about a 5.3 magnitude seismic shock.

Jeffrey Lewis of the California-based Middlebury Institute of International Studies told Reuters that the blast is estimated to be at least 20 to 30 kt.

[21] On 10 September 2016, the academics from University of Science and Technology of China[5] have released their findings based on seismic results and concluded that the Nuclear Test Location is at 41°17'54.60N, 129°4'40.80E on 00:30:01.366 UTC which is only a few hundred meters apart from the previous 3 tests (2009, 2013 and January 2016) with the estimated yield at 17.8 ±5.9 kt (An estimated yield between 11.9 kt to 23.7kt).

[23] By 13:50 Pyongyang Standard Time, state media KCNA confirmed that this was the fifth nuclear test and that the "warhead can be mounted to a missile".