US defense secretary James Mattis has warned of a "massive military response" to any threat to the US or its allies by North Korea.
Pyongyang says it has successfully tested a hydrogen bomb that could be loaded on to a long-range missile.
General Mattis spoke outside the White House after a national security meeting with President Trump. He said Trump wanted to be briefed on each of the "many military options" for dealing with the North Korean nuclear threat.
He told reporters the US would defend itself and reassured that its commitments to its allies South Korea and Japan, are "ironclad".
IN: Any threat...
OUT: North Korea
DUR: 36 secs