Stanford nuclear scientist and CISAC senior fellow Siegfried S. Hecker explains in this article in 38 North why North Korea's recent nuclear test is "deeply alarming" and what Washington's possible policy options are going forward. An excerpted passage is below:

On September 9, 2016, seismic stations around the world picked up the unmistakable signals of another North Korean underground nuclear test in the vicinity of Punggye-ri. The technical details about the test will be sorted out over the next few weeks, but the political message is already loud and clear: North Korea will continue to expand its dangerous nuclear arsenal so long as Washington stays on its current path.

Preliminary indications are that the test registered at 5.2 to 5.3 on the Richter scale, which translates to an explosion yield of approximately 15 to 20 kilotons, possibly twice the magnitude of the largest previous test. It appears to have been conducted in the same network of tunnels as the last three tests, just buried deeper into the mountain. This was the fifth known North Korean nuclear explosion; the second this year, and the third since Kim Jong Un took over the country’s leadership in December 2011. Continue reading