North Korea's first nuclear test

On October 9, 2006, North Korea set off a nuclear device in a tunnel under a mountain at Punggye-ri in its northeast. Seismic stations around the world detected the blast, and the state news agency KCNA announced a successful test the same day. Its yield was small, estimated at under 1 kiloton by most seismic analyses, much less than the bombs dropped on Japan in 1945, but it made North Korea the eighth country known to have tested a nuclear weapon.¹⁴⁵

North Korea had pursued nuclear technology since the 1960s, starting with a Soviet-supplied research reactor at Yongbyon. It joined the Nuclear Non-Proliferation Treaty in 1985, but inspectors later found signs that it had separated plutonium. A 1994 deal with the United States, the Agreed Framework, froze the Yongbyon reactor in exchange for fuel oil and promised new reactors. That deal collapsed in 2002 after U.S. officials accused Pyongyang of a secret uranium program. In January 2003 North Korea announced its withdrawal from the NPT, the first country ever to do so, expelled inspectors and restarted plutonium production. Six-party talks involving China, the U.S., South Korea, Japan and Russia did not stop it.¹

The UN Security Council responded within days with Resolution 1718, banning arms trade and imposing financial sanctions. North Korea carried out five more tests by 2017, the largest far more powerful than the first, and developed missiles that could reach the United States.²³