The time for talk on North Korea is "over", the United States said, spurning a UN response to Pyongyang's latest ICBM launch in favour of bomber flights and missile defence system tests.
Nikki Haley, the US envoy to the United Nations, said there was "no point" in holding a fruitless emergency Security Council session, warning that another weak council resolution would be "worse than nothing" in light of the North's repeated violations.
North Korean leader Kim Jong-Un boasted of his country's ability to strike any target in the US after an intercontinental ballistic missile test Friday which weapons experts said could even bring New York into range -- a major challenge to President Donald Trump.
US strategic bombers on Saturday flew over the Korean peninsula in a direct response to the launch, and on Sunday American forces successfully tested a missile interception system which the US hopes will be installed on the Korean peninsula.
Under Kim's leadership, North Korea has accelerated its drive towards a credible nuclear strike capability, in defiance of international condemnation and multiple sets of UN sanctions. The US Senate passed new bipartisan sanctions on Pyongyang on Friday.
Haley urged China, Japan and South Korea to tighten the screws on Pyongyang.
"An additional Security Council resolution that does not significantly increase the international pressure on North Korea is of no value," she said in a statement late Sunday.
"It sends the message to the North Korean dictator that the international community is unwilling to seriously challenge him.
"China must decide whether it is finally willing to take this vital step. The time for talk is over."
Analysts said the comments indicated Washington had run out of patience with the diplomatic approach, and could consider military intervention.
The latest ICBM test "poses a seemingly tangible threat to the national security of the US", said Jeung Young-Tae, director of military studies at Dongyang University in South Korea.
"Now the US will see no point in negotiation, which only helps Pyongyang earn more time to develop its weapons programmes," he said.
"Whether we want it or not, the risk of unilateral military action by the US cannot be ruled out at this point."