Lewis recalled a series of Twitter postings that Trump made in

2013 and 2014 about former NBA star Dennis Rodman's trip to North Korea, saying Trump praised "Rodman when it helped ratings of the Celebrity Apprentice, then trashed him when he didn't."

The expert also pointed out inconsistent remarks Trump made about the North.

"He called Kim Jong Un a maniac and suggested assassinating him, expressing only admiration for a 20-something stepping out of his father's shadow. And when asked about the serious issues of international diplomacy, he pivoted to a long-rant about all the money wasted on state dinners," Lewis said.

"This isn't a coherent North Korea policy, it's the ramblings of a reality television show ... To find our first hints of how Trump might approach North Korea, we need to look elsewhere. Trump is more likely to think that the way to solve the North Korea problem is serving Xi Jinping a cheeseburger, not Kim Jong Un," he said.

During the election campaign, Trump said he would pressure China to exercise its influence over North Korea as the main food and energy provider to rein in the regime in Pyongyang, saying the North is basically China's problem to fix.

Earlier this month, Trump strongly criticized China for "not helping us at all with North Korea" when "China could solve that problem." He even questioned why the US should stick to the policy of recognizing only China, not Taiwan, when Beijing is uncooperative over the North and engages in unfair trade practices. (Yonhap)