Statement from the White House:

  • Initial analysis inconsistent with reported nuclear hydrogen bomb
  • "We're continuing the work necessary to learn more"
  • 'Notable' that China and Russia echo US concerns
  • 'Rock solid commitment' on the part of the US to safeguard allies in Japan and South Korea
  • Wants North Koreans to end their provocative acts, commit to denuclearization

The White House is calling their bluff. It's extremely difficult to build a nuclear bomb but a game of nuclear chicken is a dangerous game.