[6] The United States Geological Survey reported an earthquake of 6.3 magnitude not far from North Korea's Punggye-ri nuclear test site.

[12] A later technical announcement called the device a "two-stage thermo-nuclear weapon" and stated experimental measurements were fully compatible with the design specification, and there had been no leakage of radioactive materials from the underground nuclear test.

[13][6] Photographs of North Korean leader Kim Jong-un inspecting a device resembling a thermonuclear weapon warhead were released a few hours before the test.

The North Korean government received harsh criticism after being accused of not warning civilians of the nuclear test as several children were in school when the earthquake took place.

[29] On 13 September, U.S. Intelligence was reported referring to an early yield estimate range of 70 to 280 kilotons made by the Air Force Technical Applications Center.

[33] In October 2019 a paper by the Indian Space Research Organization was published using satellite interferometric synthetic-aperture radar data to analyse surface deformations using Bayesian modelling to reduce uncertainties.

[3][34] The United Nations Security Council met in an open emergency meeting on 4 September 2017, at the request of the US, South Korea, Japan, France and the UK.

[35] Canada, China, Indonesia, Japan, Malaysia, the Philippines, Russia, Singapore, South Korea, and the United States voiced strong criticism of the nuclear test.

"[43] Defense Secretary James Mattis warned North Korea that it would be met with a "massive military response" if it threatened the United States or its allies.