US Ambassador Nikki Haley told an emergency meeting of the UN Security Council that North Korea's latest test of an intercontinental ballistic missile (ICBM) "demands that countries further isolate the Kim regime."
During a phone conversation earlier in the day, US President Donald Trump asked President Xi Jinping to cut off China's crude oil supplies to North Korea, a move that would deal a crippling blow to North Korea's economy.
Trump told the Chinese leader "that we have come to the point that China must cut off the oil from North Korea," Haley said.
"That would be a pivotal step in the world's effort to stop this international pariah," she said.
Haley also called "on all nations to cut off all ties with North Korea" and said the Security Council should take away North Korea's voting rights at the United Nations.
The council was meeting at the request of the United States, Japan and South Korea to consider next steps after three rounds of sanctions adopted in the past year failed to push North Korea to change course.
Haley said the ICBM launch had raised the threat of war.
"The dictator of North Korea made a choice yesterday that brings the world closer to war, not farther from it. If war comes, make no mistake: The North Korean regime will be utterly destroyed," she warned.
Pyongyang, on Wednesday, tested its third ICBM, which it claimed was capable of striking anywhere in the United States, snapping a two-month pause in missile launches.