An American attack on North Korea is “unacceptable” to China, a senior diplomat warned the United Nations Security Council Friday.

“The option of use of force is unacceptable,” Wu Haitao, the Chinese deputy ambassador to the U.N., said Friday. “There is no military option when it comes to the settlement of the nuclear issue on the Korean Peninsula, and [the] resort to force can only bring disastrous consequences to the peninsula.”

That’s a repudiation of Secretary of State Rex Tillerson’s latest warnings that North Korea’s pursuit of the ability to strike the United States will end in war if the regime doesn’t relent. Wu also faulted Tillerson for suggesting that China has failed to put adequate pressure on the regime, citing their implementation of past U.N. sanctions.

“China has made greater efforts and paid a higher price than anyone else,” Wu said, according to a U.N. translator. “It is irresponsible to doubt what China has done.”

That defense came minutes after Tillerson “call[ed] into question” China’s determination to force North Korea to abandon the nuclear weapons program. “[A]s Chinese crude oil flows to North Korean refineries, the United States questions China's commitment to solving an issue that has serious implications for the security of its own citizens,” Tillerson said.

U.S. officials have long complained that China has insulated North Korea from the full blast of western sanctions. In the first quarter of 2017, for instance, Chinese purchases of iron ore from North Korea spiked just as sanctions on the regime’s coal industry took affect. In September, China and Russia forced western diplomats to soften a UN sanctions resolution that would have mandated a total oil embargo.

“The last time the North Koreans came to the table, it was because China cut the oil off,” Tillerson said Tuesday. “Three days later, the North Koreans were at the table talking.”

Wu maintained that the United States bears responsibility, along with North Korea, for the simmering crisis.

“The current situation on the peninsula is not caused by any one party alone and it is not helpful to impose on any one party the responsibility of resolving the problem,” he said. “The parties concerned should move towards each other instead of engaging in mutual blaming. Still less should they try to shift their responsibility to others.”

Chinese and Russian officials have argued that the U.S. and South Korea should suspend military exercises in the region, saying that such war games provoke the northern regime into additional aggressions. But Tillerson put the onus on North Korea to make talks possible by halting nuclear tests and missile launches, while adding that the United States is willing to talk.

“North Korea must earn its way back to the table,” Tillerson said.