WASHINGTON: US President Donald Trump says he is "very disappointed" with China for not doing enough to stop North Korea's weapons programme.

Writing on Twitter, he said he would not allow China to "do nothing" about the reclusive state. His comments came a day after Pyongyang test-fired its second intercontinental ballistic missile (ICBM) in a month.

It later claimed the test proved that the entire US was within striking range of its weaponry. On Saturday, two US B-1 bombers conducted exercises over the Korean peninsula with South Korean and Japanese planes.

The move was a "direct response" to the North's two ICBM launches, and "part of the continuing demonstration of ironclad US commitment to our allies", the US Pacific Command said.

"North Korea remains the most urgent threat to regional stability," Gen Terrence J O'Shaughnessy, Pacific Air Forces commander, added in a statement.