“I think it’s increasing every day, which means that we are in a race, really, we are in a race to be able to solve this problem,” McMaster told an audience on Saturday at the Reagan National Defence Forum in Simi Valley, California when asked if North Korea’s launch of an intercontinental ballistic missile on 28 November had increased the chance of war.

McMaster noted that Beijing’s “tremendous coercive economic power” over North Korea.

“There are ways to address this problem short of armed conflict, but it is a race because he’s (Kim Jong-un) getting closer and closer, and there’s not much time left,” McMaster said.

With every missile launch or nuclear test, Kim has improved his country’s capabilities, McMaster said.China should take unilateral action to cut off North Korean oil imports, CNN quoted McMaster as saying. He said that both he and Trump felt that a 100 percent oil embargo would “be appropriate at this point”.

On military options, McMaster acknowledged that given North Korea’s fielding of conventional artillery and rockets aimed at Seoul, South Korea, “there’s no military course of action that comes without risk”.

However, he said that Pyongyang’s actions had made America’s alliances with Japan and South Korea “stronger than ever”.