What geology reveals about North Korea’s nuclear weapons – and what it obscures

North Korea’s leader, Chairman Kim Jong Un, clearly is in no hurry to demilitarize his country. In the wake of two historic yet unproductive summits with President Trump, Kim made a state visit in April to Moscow, where he made clear that his country will not give up its nuclear weapons without international security guarantees. North Korea also tested what appeared to be short-range missiles on April 18 and May 4.