Uncertainty over a summit between the US and North Korea is disappearing fast.

North Korean leader Kim Jong-un met with South Korean President Moon Jae-in for the second time to reaffirm his commitment to denuclearize his country, as US President Donald Trump seeks to reinstate the summit with Kim he canceled.

But hasty optimism should have no place on the path to the summit. There remain difficult issues to work out between the US and the North until the Korean Peninsula is completely denuclearized.

Moon had a surprise meeting with Kim on Saturday, the second inter-Korean summit in a month. It is also the first time that an inter-Korean summit was held unannounced beforehand. This reflects a precarious situation in which preparations for the Trump-Kim summit could veer onto an unintended course at the slightest slip. Under this atmosphere, Moon acted as a broker or facilitator by meeting with Kim three days after having talks with Trump.

Moon said in a news conference Sunday -- a day after the summit -- that Kim made clear his commitment to denuclearize his country completely. He said Kim requested the summit.

During the meeting, Moon conveyed Trump’s message that if Kim carries out his pledge to dismantle nuclear arsenals in the North completely, Washington will end their hostile relations and cooperate with the North economically.

Kim’s reaffirmation of his will to denuclearize the North was met by Trump’s positive remarks on their summit. The US leader said Saturday that things are moving “very nicely” toward a summit with Kim on June 12 in Singapore. Trump said, “We’re looking at June 12 in Singapore. It hasn’t changed.”

In conjunction with the second inter-Korean summit, his words strongly suggest the summit will likely happen as scheduled.

The second summit between Moon and Kim is expected to boost inter-Korean dialogue, which faltered after their first summit on April 27. In their second talks, they agreed to hold a high-level inter-Korean meeting on June 1, followed by military and Red Cross talks.

The second summit is also meaningful in that it was held swiftly and without formalities. It greenlighted follow-ups to the first summit and for closer inter-Korean relations. But given the delicate situation regarding the US-North Korea summit, the Moon government will have to moderate the pace of inter-Korean dialogue to some extent until it is held.

The second inter-Korean summit was held apparently to ensure more stable progress to the Trump-Kim summit, which had looked derailed but now appears to be back on track. Now that Kim has received Trump’s messages through Moon, he needs to put his trust in them and try to get involved more proactively in working contact to realize their summit. If Kim’s will to denuclearize his country was not confirmed definitely, it will be revealed in the stage of working negotiations.

Undoubtedly, the core question of the US-North Korea summit is how to denuclearize the North. Therefore, the key to its success lies in the way to find common ground between the North’s “staged and simultaneous approach” and the US’ “all-in-one or quickest possible” denuclearization.

It is not clear yet whether Pyongyang has accepted the US’ demands, but expectations are high that these issues will be settled in order to realize the summit.

It is time for Trump and Kim to leave any bad feelings behind and move on. Rude criticisms should be avoided amid the difficult process to find solutions to denuclearize the peninsula. Whether their summit will happen successfully depends on how working negotiations to narrow their differences turn out.

Both sides must not let trivialities stand in the way and instead move forward to dialogue with faith and a long-term perspective. Fifteen days are left to June 12. Until then, they should maintain their commitment and come up with a concrete road map.

In order to achieve their shared goals of denuclearization and a regime guarantee, Washington and Pyongyang must communicate with each other as often and as directly as possible, and refrain from words and deeds that could hurt trust.