US Defense Secretary James Mattis (L) speaks to the press with Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, about the situation in North Korea at the White House in Washington, DC, on September 3, 2017. The US will launch ‚massive military response‘ to any threat from Pyongyang, Mattis said. US President Donald Trump on Sunday denounced North Korea’s detonation of what it claimed was a hydrogen bomb able to fit atop a missile, saying the time for ‚appeasement‘ was over and threatening drastic economic sanctions.