The government has officially confirmed that North Korea conducted a nuclear test on October 9th.

The Ministry of Science and Technology said Wednesday that radioactive forms of xenon, a tell-tale sign of a nuclear explosion, have been detected in South Korea for the first time since the North announced its underground nuclear test.

A government official said the assessment also took into account seismic wave analysis conducted by the Korea Institute of Geoscience and Mineral Resources and information provided by the United States.

The official said the South Korean government has concluded that given the size of the seismic wave and explosion, Pyongyang’s nuclear test was a technical failure but not a political one.

The official added it would not pose a technical challenge for North Korea to increase the size of such an explosion in the future.