US President Donald Trump and North Korean leader Kim Jong-un held a historic summit in Singapore on Tuesday, taking the first step toward a peacefully denuclearized Korean Peninsula.

The first summit between a sitting US president and North Korean leader in 70 years since the division of Korea in 1948 raised hope for a new era of reconciliation between the two countries.

Trump said at a signing ceremony for a “comprehensive” joint statement with Kim after the summit that he had developed a “very special bond” with the North Korean leader. Kim said he and Trump “decided to leave the past behind.” Trump hoped to meet Kim many times, adding he would invite him to the White House when the time is right.

In his news conference in Singapore after the summit, Trump said Kim reaffirmed his commitment to denuclearization. The US president said the details are to be worked out in follow-up talks and the process will begin quickly.

The summit fell short of expectations of a road map for denuclearization, but the issue of dismantling the North Korean nuclear program and assuring the security of its regime -- two key agenda items of the summit -- are as difficult to solve as a tangled knot.

The summit in Singapore is just a beginning. The North Korean nuclear issue cannot be solved at a single stroke.

Difficult as it may be for now to prejudge follow-up contacts, working negotiations will likely face rough-going in such stages as the inspection and verification of nuclear materials and sites.

Until the denuclearization process is completed, both Pyongyang and Washington must stick to sincere efforts to keep their pledges, while related countries must keep cooperating with them.

What matters most in doing so is to build and maintain mutual confidence. The starting point is to have as frequent contacts as possible. Any promise will be nothing more than a piece of paper unless trust underscores it.

Here, the South Korean government’s role between the North and the US will be ever more important.

South Korean President Moon Jae-in has played the role of a mediator to initiate a detente on the peninsula and arrange the summit. His role as such will likely move him into the spotlight again on the path to actualizing the results of the summit.

For Moon to perform the role well, it is important to uphold a solid Korea-US alliance. The alliance is the basis of South Korea’s diplomacy and security. At its core are the US forces stationed in Korea. They have been a balancing force on the South Korean side in East Asia, where China and Russia seek to expand their influences. This security environment will not change even after the North gives up its nukes. Trump’s remarks in the news conference that he will stop the “war games,” or military exercises, with the South are worrisome.

Kim’s denuclearization commitment will be tested by the concrete actions he takes.

Pyongyang must declare its nuclear capability frankly, accept inspections of both declared and undeclared sites readily and disable its nuclear technology irretrievably.

If the North starts to fulfill its denuclearization pledge, the US must not be stingy in taking steps to assure its regime security.

However, the US and international community should not act rashly regarding the lifting of sanctions. Sanctions are the leverage to prod Pyongyang to take quick actions to dismantle its arsenal of nuclear weapons. Their impetuous lifting could let out the steam of denuclearizing momentum. Particularly, a back door for illicit trade must not be opened.

North Korea expects denuclearization to open the way for its economic reconstruction. When its economic issues surface, South Korea and China are expected to bear the burden.

But the Moon administration should not drive its inter-Korean projects, economic assistance in particular, too quickly, until the nuclear issue is solved completely. The end game to settle the North Korean nuclear problem has just started.

Economic relief needs go beyond one-sided support. It can be meaningful when it accompanies reform and the opening of North Korean society. Blind assistance is prone to regress to the repetition of past failures. Inter-Korean relations must keep in pace with denuclearization and US-North Korea relations.