If confirmed, 2016 would become the first year to see multiple nuclear tests by North Korea.


At 9:30 a.m. on Friday, a 5.3 magnitude seismic event was detected northwest of North Korea’s Punggye-ri nuclear testing site, suggesting that the country has carried out its fifth nuclear test. The United States Geological Survey reported the depth of the quake at 0 kilometers, strongly suggesting that Friday’s event was a nuclear test.

The test makes 2016 the first year since North Korea began testing its nuclear devices underground to see more than a single nuclear test. North Korea previously tested nuclear weapons in January 2016, February 2013, May 2009, and October 2006. The 5.3 magnitude quake would put the expected yield of this test roughly in the 20 to 30 kiloton range, notes North Korea-watcher and nuclear weapons expert Jeffrey Lewis. (Yield estimates this early on, however, are difficult to pinpoint, given measurement uncertainty.)

North Korea claimed that its January test this year involved a thermonuclear device, a claim that most nuclear experts doubted that Pyongyang had developed a fully staged bomb (also known as a hydrogen bomb). The increased range estimate for this test suggests that even if Pyongyang hasn’t managed to fully stage a thermonuclear device, it is making progress with a boosted fission bomb.

Friday’s test also coincides with the country’s September 9 Foundation Day. North Korea has made a habit of carrying out major tests of weapons systems and nuclear weapons on significant dates. This year’s first nuclear test, for example, roughly coincided with Kim Jong-un’s birthday. North Korea additionally had recently dispatched a senior diplomat involved in nuclear talks to China, its historical partner and benefactor. Though reports did not specify a reason for the visit, Choe Son Hui, the North Korean diplomat, could have given Beijing notice of an impending test. Despite a return to increasing diplomatic contact between the two countries this summer, their bilateral relationship remains exceptionally strained and has been under pressure since 2013.

Regardless of the circumstances that led to the test, Friday’s explosion marks the continuation of an exceptionally active year of nuclear and missile testing from North Korea. In addition to the two nuclear tests this year, Pyongyang has been repeatedly testing various ballistic missiles, including its first submarine-launched ballistic missile. Earlier this week, during the G20 meeting in Hangzhou, China, Pyongyang launched previously unseen Scud-ER missiles.

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This article will be updated as more information becomes available.