McCain said that China is the short-term key to the North Korea problem.

"It's not in China's interest to see this kind of confrontation between the United States and a very unstable young man. And so I would hope that the president's relationship that he developed down in Florida with the Chinese leader will yield some benefits in breaking this continued progress towards this capability of threatening the United States of America," he said, referring to President Donald Trump's summit with Chinese President Xi Jinping.

China should understand that th US "cannot live with a situation where North Korea has this kind of capability."

Since his first summit meetings with Xi earlier this month, Trump has repeatedly praised China for trying to increase pressure on the North, citing Beijing's decision to return coal imports from the North as an example. Trump has also held out the prospect of a better trade deal with the US if China solves the problem.

China is North Korea's last-remaining major ally and a key provider of food and fuel supplies. But it has been reluctant to use its influence over Pyongyang for fears that pushing the regime too hard could result in instability in the North and hurt Chinese national interests.

Analysts doubt how far China can go in pressuring Pyongyang, saying China has often increased pressure on the North in the past, especially when Pyongyang carried out nuclear and missile tests and other provocative acts, but it never went as far as to cause real pain. (Yonhap)