Kim Jong Un inspected a new plant that makes weapons-grade nuclear material on Wednesday and said Pyongyang plans to “beef up our state’s nuclear forces at an exponential rate,” according to a report from state-run media.

North Korean leader Kim Jong-un has visited a newly launched nuclear material production facility, vowing to "exponentially" strengthen the country...

Of the planned increase, North Korean leader Kim Jong Un said: "This signifies an amazing, successful change that is beyond rhetorical description, a historic event that has set…