Washington(CNN) Secretary of State Rex Tillerson said Thursday that China threatened the North Korean government with sanctions if it undertook another nuclear weapons test.
Tillerson made his comments on Fox News ahead of a visit to the United Nations and amid rising tensions over the North Korean nuclear weapons program.
"They confirmed to us that they had requested that the regime conduct no further nuclear test," Tillerson said of the Chinese. "In fact, we were told by the Chinese that they informed the (North Korean) regime that if they did conduct further nuclear tests, China would be taking sanctions action on their own."
China remains one of North Korea's only allies and is responsible for much of the heavily-sanctioned nation's economy.
President Donald Trump told Reuters on Thursday that Chinese President Xi Jinping is "a very good man" and is trying to pressure North Korea.
"I believe he is trying very hard," Trump said. "He loves China and he loves the people of China. I know he would like to be able to do something, perhaps it's possible that he can't."
Tillerson said he was hopeful about cooperation with the Chinese. He also said he believed North Korean leader Kim Jong Un is a rational actor.
"He may be ruthless," he said. "He may be a murderer. He may be someone who, in many respects, we would say by our standards is irrational. But he is not insane."
Trump was less certain, telling Reuters that he had "no opinion" on whether the North Korean dictator was rational or not.
"I hope he's rational," Trump said.
North Korea conducted its fifth nuclear test last fall, and observers have said a sixth test could be near. Additionally, North Korea has undergone a series of missile tests in recent months, and while many have failed, experts have said the nation's nuclear arsenal could pose an immediate threat to the mainland US if it progresses.
Tillerson said the US approach to North Korea under Trump is different from the Obama administration's in terms of both "intensity" and "expectations," particularly what it requires of China.
"We're asking a lot of the Chinese," Tillerson said. "I think in the past, the assumption has been the Chinese would only take limited action. We're going to test that assumption."
Tillerson said the added pressure is compounded by the growing threat the North Korean nuclear program could pose to China. He said the Trump administration is seeking the same thing as China: A North Korea without nuclear weapons.
"We do not seek regime change in North Korea," Tillerson said. "We're not seeking a collapse of the regime."
China said it would ban coal imports from North Korea for the rest of 2017 in February, although North Korean ships docked at a Chinese port earlier this month, drawing some scrutiny.
The UN Security Council, of which both the US and China have veto power, voted last fall to impose a new round of sanctions on the North Korean economy.
North Korean official Sok Chol Won told CNN on Wednesday that the country's government would never stop nuclear and missile tests "as long as America continues its hostile acts of aggression."