The US ambassador to the United Nations on Thursday said China can and must do more to force North Korea to halt its nuclear and missile programs.
Ambassador Nikki Haley said President Donald Trump would raise the issue next week at his first summit with Chinese leader Xi Jinping.
And, amid reports that Pyongyang is preparing another banned nuclear test, Haley said Washington would not settle for holding another UN debate.
"I have no patience for it, and it is not helping anyone. And it's not about me. This administration has no patience for it," she said.
"Look, can we change the way North Korea thinks? No. They're not going to cave. China can, and that's the part we want to look at.
"I know China says they're worried about North Korea. I know China wants to see North Korea stop with the testing. Prove it. Prove it."
China, Haley said, could prove it is serious about restraining its rogue neighbor by enforcing an embargo against North Korean coal exports.
China announced it was halting coal imports from North Korea on February 18 -- although in that month as a whole the trade still increased by 40 percent.
Haley alleged that Beijing still allows the North to trade coal "through other ways" and demanded it "take this as seriously as the rest of the world does."
Trump and Xi will meet next week at the US leader's golf resort in Florida, the first face-to-face meeting between the heads of the world's two greatest powers.
The talks are seen as crucial for setting the tone in future relations, but Haley warned that -- on North Korea -- Trump would demand results.
"I think you're going to see them talk very much about the responsibility that we believe China has," Haley said.
"The fact that we don't have the patience to sit here and see it go round and round any more. And the fact that we want action."
And, asked if Pyongyang goes ahead and conducts another bomb or missile test, Haley seemed to leave open the door to tougher US unilateral action.
"If something happens, if this continues down the path that we're going on, I can tell you we're not just going to sit down and say 'Oh, they did it again,'" she said.
"This is something that is very serious. This is something the administration is making a priority. And this is something we absolutely expect China and Russia to respond to."