South and North Korea held a historic summit in the truce village of Panmunjeom on Friday, taking the first step toward denuclearization and rapprochement.

The summit began after South Korean President Moon Jae-in and North Korean leader Kim Jong-un met for the first time at the military demarcation line in the Demilitarized Zone and vowed sincere efforts to make progress.

It has more significance than the past two summits in 2000 and 2007 in that it is expected to bring about a big change in conjunction with the first-ever US-North Korea summit expected in late May or early June.

Just four months ago, it was unimaginable for a summit to happen between the two Koreas and a summit between the US and the North to be arranged.

Late last year, Kim declared his country’s nuclear program was complete, and then suggested his country participate in the PyeongChang Winter Olympics. Seizing Kim’s apparent change of strategy, Moon worked hard to arrange the historic meetings.

This is only the beginning. The last thing that should be done now is to repeat past mistakes.

Under a six-party accord in 2007, North Korea took a dramatic step toward dismantling its nuclear arsenal by blowing up a cooling tower at a nuclear reactor complex in 2008. The US took the North off a list of terror-sponsoring states in exchange. But in 2013, Pyongyang resumed nuclear tests.

The US has made it clear that there should be no “phased compensation” for negotiations with North Korea on denuclearization. US President Donald Trump said Tuesday that complete denuclearization of North Korea means “They get rid of their nukes.”

These can be viewed as an expression of determination not to repeat past mistakes. A phased, gradual approach is cited as one of the major reasons behind the failure to denuclearize the North.

Dismantling the nuclear program of a country is a complex process based on sincerity. Pyongyang’s sincerity will be tested when it begins to undergo related procedures including exhaustive inspections.

The primary goal of past accords on the North Korean nuclear program was to freeze it first.

Preventing new programs and scrapping nuclear materials followed suit. But the present situation is different from that time when the North was at the beginning of developing nuclear bombs and missiles. Denuclearizing a state is never an easy job. South Korea, the US and the international community must work on it in full force. Not a single warhead must remain hidden.

Pyongyang has pursued a policy of parallel development of nuclear weapons and the national economy. It is mistaken about the situation if it thinks it has only to focus on the economy through summit diplomacy because it has nearly completed its nuclear development.

If it does a flip-flop on denuclearization or attempts to hide any part of its nuclear program, the consequences will be completely different from before.

Sitting at the table for dialogue is just a start. Actions speak louder than words. If enough pressure is not kept up, the need to follow through with its commitment to scrap nuclear programs will vanish.

The US has vowed to maintain maximum pressure on the North until it takes concrete actions for complete denuclearization. South Korea must take a position consistent with the US.

Sanctions can be eased only when substantial progress is made in denuclearizing the North. However, Beijing displays a lax attitude that sanctions can be eased if needed to further dialogue and negotiations.

But the international front of sanctions should not be shaken at a time when the North has just come to the start of denuclearization.

It appears obvious that the security environment of the Korean Peninsula has turned toward denuclearization and rapprochement. South Korea has scheduled a summit with the US in mid-May before the Trump-Kim meeting. Seoul and Washington will come up with a road map for denuclearization.

North Korea’s nuclear program is a matter that threatens the South the most, but it can only be resolved at the US-North Korea summit rather than through the inter-Korean summit because the South cannot achieve the goal alone.

Seoul must keep up close coordination with the US to establish a nuclear-free peace regime.