Negotiations between the US and North Korea to prepare for their historic summit are entering the final stretch after a roller coaster ride which once went to a short-lived cancellation.

US President Donald Trump announced on Friday that his June 12 meeting with North Korean leader Kim Jong-un in Singapore would go ahead. This news came after senior North Korean official Kim Yong-chol hand-delivered a letter from Kim Jong-un to the president.

Trump said Singapore would be “a get-to-know-you kind of situation” and the beginning of a “process.”

This indicates that although Trump will negotiate with Kim for a complete, verifiable and irreversible dismantlement of the North Korean nuclear programs, he does not expect quick and complete results.

It forewarns again that the road to denuclearization of North Korea will never be smooth.

The most important thing to do now with seven days remaining before the summit is to work out details on the method to eliminate nuclear arsenal in the North. Both sides need to focus on what steps the North will take in the early stage of denuclearization and what the US will offer in return.

News media speculate that the US demands it take out nuclear warheads and intercontinental ballistic missiles from the North, while the North keeps to the position that the US should offer concrete compensation, such as easing or lifting sanctions and guaranteeing the security of its regime. As for the approach to denuclearization, Washington wants a quick all-in-one appraoch, while Pyongyang a phased one. The quicker the denuclearization is complete, the better. If it takes many stages and a long time, it will likely be hard to achieve the goal.

Against this backdrop, Trump’s mentioning of the declaration of an end to the Korean War attracts attention.

A deal to declare the termination of the war is worth being pushed for as a transitional way to guarantee the North Korean regime at the initial stage of denuclearization. It is not only non-binding but also politically less burdensome than a peace treaty or the establishment of diplomatic relations which require ratification from the Congress.

A promise not to invade North Korea will serve as security assurance to Pyongyang until a peace regime is established.

If negotiations on the declaration progress well, the US and the North are likely to consider an option of President Moon Jae-in signing it after the Trump-Kim summit.

Even as officials from Washington and Pyongyang tried to bridge their differences over the summit agenda, US Secretary of State Mike Pompeo warned after meeting with Kim Yong-chol in New York, “the North Korean regime will need to show “bold leadership.”

This may be a common negotiation rhetoric, but implies that the two countries still have a gap to fill.

If the North wants its regime to be guaranteed through ratification, it will have to assure the Congress with its bold early-stage measures. In this light, letting the US take out its nuclear warheads is a necessary condition to earn a Congress-assured guarantee of the North Korean regime.

In the end, the key to denuclearization is Kim Jong-un’s firm determination. If he is sincere, he will take related actions as quickly as possible. If not, he will only raise suspicions of trying to drag things on while seeking as much compensation as possible.

He still seems to dither. When he met with Russian Foreign Minister Sergey Lavrov recently, he said he wanted a phased denuclearization. Though Kim kept a low profile after being taken aback by Trump’s cancellation of the summit, he still shows a stance that it is difficult to back down on his terms of denuclearization. Even if Kim delivered his personal letter apparently on his commitment to denuclearize the North, the US cannot but question his sincerity.

Pyongyang has a track record of breaking its promises in the implementation phase after reaching agreements. The success of the summit will depend on its faithful implementation of agreements.

If Kim Jong-un wants to be assured of his regime, he must make a big decision first to dismantle nuclear programs in the North completely and quickly.