The nominee for U.S. ambassador to the United Nations said on Wednesday that the United States should work with its South Korean and Japanese allies, but also with China and Russia, to denuclearize North Korea.

Linda Thomas-Greenfield made the remarks during her confirmation hearing before the Senate Relations Committee when asked about the North Korean nuclear issue. 

The nominee said the U.S. certainly has to reengage with its allies, stressing that it is not something the country can do on its own. 

Thomas-Greenfield said the former Donald Trump administration may have failed to rid the North of its nuclear weapons because it tried to go "alone."

She said that reengaging with South Korea and Japan, as well as with China and Russia, particularly to push for their respect for a sanctions regime against North Korea, is going to be really important.