The United States is moving to cut off ties with China, seeking to halt the president’s efforts to leave the country as tensions escalate over North Korea’s nuclear weapons program.

The White House announced Monday that it was sending a letter to the Chinese government urging the Chinese leadership to prevent the United States from engaging in trade with North Korea.

The administration said in the letter that Trump’s attempts to cut a deal with China were “untenable,” and the United Nations Security Council must act.

Trump’s administration has been trying to convince Beijing to ease its economic sanctions on Pyongyang, but the Chinese are refusing to do so.

China has said the U.S. has been “unable” to comply with its demands and is ready to meet the demands.

“China has never allowed its citizens to enter its territory,” the White House letter said.

“We are concerned that the United State’s efforts are untenable and will not succeed.”

The White and congressional leaders met Monday in New York to discuss North Korea, which is under U.N. sanctions imposed on North Korea following its third nuclear test in January.

The United States says Pyongyang’s nuclear and missile programs are a threat to the world.

China is North Korea`s main ally, and Beijing has repeatedly said it would not abide by U.n. sanctions on North Korean citizens.