The United States called on China on Thursday to end "business as usual" with its ally North Korea after Pyongyang defied world powers by announcing it had tested a hydrogen bomb.
US Secretary of State John Kerry said he made clear in a phone call with Chinese Foreign Minister Wang Yi that China's approach to North Korea has not succeeded.
"China had a particular approach that it wanted to make, that we agreed and respected to give them space to implement that," Kerry told reporters. "Today in my conversation with the Chinese I made it very clear that has not worked and we cannot continue business as usual."
China is the North's main economic and diplomatic backer although relations between the two Cold War allies have cooled in recent years.
The vast majority of North Korea's business dealings are with China, which bought 90 percent of the isolated country's exports in 2013, according to data compiled by South Korea's International Trade Association.
North Korea carried out a nuclear test on Wednesday, although the U.S. government and weapons experts doubt Pyongyang's assertion that the device it exploded was a powerful hydrogen bomb.
The test angered both the United States and China, which was not given prior notice.
The top U.S. diplomat, Kerry said he and Wang agreed to work closely to determine what measures could be taken given increasing concerns about the nuclear test.