Donald Trump has praised China's President Xi Jinping for his handling of North Korea, calling him "a very good man" who loves his country.
The US president told Reuters he would like to solve the crisis diplomatically but that it was "difficult" and a "major, major conflict" was possible.
He also said it had been "very hard" for Kim Jong-un to take over North Korea at such a young age. The UN Security Council is meeting to discuss North Korea on Friday.
US Secretary of State Rex Tillerson has said China has told the US it will impose sanctions on North Korea if it conducts further nuclear tests.
US soldiers prepare for a military exercise near the border between South and North Korea in Paju, South Korea (14 April 2017).
Shortly after being elected, Mr Trump had accused China of not doing enough to rein in North Korea, and suggested the US could take unilateral action.
But in a wide-ranging interview with Reuters from the Oval Office, Mr Trump - who met Mr Xi earlier this month - said the Chinese president "certainly doesn't want to see turmoil and death".
"He is a very good man and I got to know him very well.
"He loves China and he loves the people of China. I know he would like to be able to do something, perhaps it's possible that he can't," he said.