Medeiros also said the North will likely be "the single most defining geopolitical challenge" for Trump.

"North Korea doesn't want to give up its nuclear weapons. Nuclear weapons are key to its survival," Medeiros said. "Talks for North Korea are really about getting sanctions relief, playing for time, playing for advantage, trying to get sanctions lifted."

"What I worry about is Trump, understanding that his options are relatively limited, feeling like he's a great negotiator, as he tells us all, that he might give talks a try only to learn the lesson that several other American presidents and Japanese prime ministers and South Korean presidents have learned, which is, the North Koreans really aren't serious about talks at all," he said.

Calls for opening negotiations with the North have significantly grown in the US since last year as Pyongyang dangerously accelerated its weapons development, including conducting two nuclear tests and a number of missile launches last year alone.

Pro-diplomacy experts have called for negotiating a freeze, rather than denuclearization, with the North. Earlier this week, the New York Times also made a similar case, saying denuclearization isn't realistically attainable and that time is not on the US side.

But many other experts say the US should never settle for a freeze because it would amount to accepting the North as a nuclear weapons state. Even if the North agrees to a freeze, the regime would still be running its nuclear and missile programs at undeclared facilities while rejecting full verification by outside experts, they said.

Robert Gallucci, who negotiated the 1994 nuclear freeze deal with Pyongyang, also told the House Foreign Affairs Committee earlier this month that the US should not seek anything short of North Korea's complete denuclearization, saying a freeze is "unrealistic and dangerous."

Entering into negotiations with the North without the US declaring its goal of a non-nuclear North Korea would "appear to have the United States legitimize the North's nuclear weapons status, and thus increase the likelihood that before too long South Korea and then Japan would follow suit," Gallucci said. (Yonhap)