NK had the first successful detonation of a nuclear device in 10/2006. W and the neo-cons didn't have an answer. The next four, were 5/2009, 2/2013 (timed with Obama's State of the Union Address), 1/2016 and 9/2016. BTW the last nuclear device was estimated at 10-kilotons and ten times the strength of the 2006 device.  NK also launched an ICBM from a submarine in early-2016. I skipped the bevy of missile launches. Obama had 8 years and we have nuclear armed NK. Trump has 7 months. My guess is that this game of "war chicken" with KJU will go on until NK makes on provocation too many. Yet everything NK has done was solely at the direction of China.