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North Korea's diplomatic olive branches ahead of the Winter Olympics shouldn't be mistaken for the end of Kim Jong Un's missile and nuclear tests, according to a former U.S. ambassador and a top analyst.

PyeongChang 2018 will be the first Olympic Games to feature athletes from the South and North on a unified team — even though the neighbors are technically still at war.

North Korean leader Kim is sending a 550-member delegation, including athletes and cheerleaders, following rare face-to-face talks between the rivals.

"There'll be a positive feeling that ... we've somehow turned the corner and are heading to a solution," said Chris Hill, the former ambassador to South Korea, referring to the recent Olympic cooperation.

But, he added, "I don't think by any means North Korea is prepared to denuclearize at this point."

North Korea ramped up its missile and nuclear program last year, testing its first three intercontinental ballistic missiles and most powerful nuclear weapon to date.

This was met with international sanctions as well as a flurry of insults between President Donald Trump and North Korean state media.

The Olympics appear to have acted as a peg on which to hang a certain degree of cooperation between the two Koreas that has not been seen in years.

As well as the face-to-face meetings and joint participation in the games, the South also agreed to pause the joint military exercises it holds each year with the U.S.

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"I think what North Korea is trying to achieve with this opening of dialogue with the South is as if to say, 'Look we have nuclear weapons, we're not going to get rid of nuclear weapons, but we are prepared to be very good neighbor,'" said Hill, who is currently chief adviser to the chancellor for global engagement at the University of Denver. "It’s an effort to present a sense of normalcy to their country, the fact that they are somehow, in their view, a member of the international community in good standing."

However, Hill warned there was a danger that the North was trying to divide the U.S. from its South Korean ally by taking a hard line toward Washington while cozying up to Seoul.

They may want to "expose some difference between the outlook between the U.S. and South Korea," he said.

North Korean leader Kim Jong Un visits the Pyongyang Teacher Training College in a photo released by the state-run Korean Central News Agency on Jan. 17. KCNA / via Reuters

This echoes concerns by officials in the Trump administration. Secretary of State Rex Tillerson and national security adviser H.R. McMaster have both warned that North Korea must not be allowed "to drive a wedge" between the allies.

Hill said this new-found diplomacy could continue after the games, but any hope that it might lead to the North making any concessions over its weapons program appeared faint at best.

"I don't think we've seen the last missile launch from North Korea," he said. "I think some of the goodwill of these Olympics will certainly dissipate over the coming months."

This view is held by many experts including Jeffrey Lewis, a nuclear policy expert at the Middlebury Institute of International Studies at Monterey, California.

He told NBC News that he had "no doubt whatsoever" Kim's regime would resume testing in the near future.

"I think things will get better for the Olympics — or at least I'm hopeful that they will," he said, but added, "I think there is exactly no chance the North Koreans will abandon their nuclear weapons."

Like the former diplomat, Lewis pointed out that North Korea's tests aren't designed merely to make a political statement, but are rather necessary practical stepping stones on its route to building a viable nuclear weapon capable of hitting the U.S.

"They've only tested their biggest missile once," he said. "And I expect that they will test it many more times before they have the kind of confidence in it that they want."

Analysts say that based on the current evidence it's hard to prove or debunk North Korea's claim that it can now hit faraway American targets such as New York or Washington.

What North Korea thinks is an acceptable level of confidence, Lewis added, is likely different than what U.S. officials would be happy with.

The official emblem of the 2018 PyeongChang Olympics is displayed in downtown Seoul, South Korea. Lee Jin-man / AP file

"In the United States, we would say a nuclear weapon was not reliable if it went off with something like 85 percent of the power that we thought it would explode with," he said. "I think Kim Jong Un is probably fine with an 85 percent successful nuclear weapon."

Lewis said North Korea is concerned that Kim could end up driven from power like former Iraqi dictator Saddam Hussein or Libya's Moammar Gadhafi.

"They look at those nuclear weapons as the best insurance they have that that won't happen," he added.

North Korea has said in public statements that it wants an official end to the Korean War. The conflict was halted by a 1953 armistice but no peace treaty has been signed. It also wants nothing short of full normalization of relations with the U.S. and to be treated with respect and as an equal in the global arena.