South Korea's military has fired missiles into the sea in a simulation of an attack on North Korea's nuclear test site a day after Pyongyang set off its largest ever nuclear test explosion.

In Washington, US Defense Secretary Jim Mattis bluntly warned that the US will answer any threat from the North with a "massive military response."

Earlier, President Donald Trump threatened to halt all trade with countries doing business with the North, a veiled warning to China, and faulted South Korea for its "talk of appeasement."

North Korea tested what leader Kim Jong Un's government claimed was a hydrogen bomb.

That would be a major advancement in Pyongyang's long-sought goal of an arsenal of nuclear-tipped missiles that can hit the United States.

Source: Khaleej Times