President Moon Jae-in will pay a four-day state visit to China next Wednesday at President Xi Jinping’s invitation. It will be his first trip to the country since taking office in May.

The top item on their summit agenda is North Korea’s nuclear and missile programs, which have reached a critical stage after it test-fired an apparent intercontinental ballistic missile last week and conducted its most powerful nuclear test on Sept. 3.

Moon must demand Xi put stronger pressure on the North, as now is the time for the international community to act against Pyongyang in unison. Pressure until it cannot keep up the programs any more is the only realistic way to resolve the North Korea issue without war, and the whole world knows China holds the key to such pressure. He must emphasize that something bold, such as China’s suspension of its oil supply to the North, needs to be done to bring the North to the negotiation table.

Although China grumbles that it has done enough, it needs to understand clearly that the goal of pressure is not to bring down the country but to prevent the peninsula from taking the course of an armed clash.

Beijing should also know that the completion of the North Korean nuclear missile program will never be good for China, either, because it can lead to nuclear armament of South Korea and Japan, which it opposes.

At the summit, both leaders must narrow their differences over the question of pressuring the North.

The North Korea issue has reached a critical point in which words like a nuclear war are mentioned openly even in China. The US Central Intelligence Agency is said to have warned President Donald Trump that there is only a “three-month window” in which the US can halt North Korea’s ICBM program. Undoubtedly the first target of a North Korean missile is South Korea. Moon must not evade straight talk about the North Korea problem to foster a friendly atmosphere in the summit.

The international community will be watching the summit with great expectations for a South Korea-China solution to stop Pyongyang’s nuclear and missile program and prevent pre-emptive US attacks on North Korea.

Moon and Xi must also remove differences between their countries over the US Terminal High Altitude Area Defense antimissile system. South Korea understands that conflicts over the system were over, with an agreement to normalize bilateral ties, while China does not seem to see things the same way. Whether the row has ended is still in doubt, considering senior Chinese officials’ remarks and state media reports demanding the withdrawal of the system from Korea and China’s partial lifting of the ban on group tours to Korea. Seoul does not want Beijing to raise an issue with the system, but cannot exclude the possibility of Xi bringing it up in the summit.

Restrictions on group tours and all other retaliations should be lifted through Moon’s state visit. Moon must note ongoing retaliation against Lotte, the company which offered a site for the system, and obtain a definite promise to stop them.

South Korea and China can go back on track for a new era only after scores are completely settled over the system. Bringing the issue into conversation will throw a wet blanket over the efforts to normalize their ties. Beijing should know that South Korea will not need the system without North Korea’s missile threats.

South Korea and China are partners indispensable to each other in many ways. Moon’s upcoming state visit to China should serve as an occasion to build mutual trust of the two countries.

Xi has vowed to contribute to the peace and stability of the world whenever he got a chance to, but if he weighs only the interests of his country, his avowal will be nothing but lip service and hypocrisy.

The summit must open up a way to bridge a gap between the two leaders.