Foreign ministers of South Korea and China agreed Wednesday in Beijing to work toward President Moon Jae-in’s state visit to China next month. His visit will boost the two nation’s efforts to mend ties.

State visits are considered the highest expression of friendly bilateral relations between two states. Most nations host fewer than 10 state visits per year. A state visit is received customarily once per country while its head holds office.

The deal to use the diplomatic event that South Korea and China can use only once during Moon’s presidency reflects their determination to accelerate the restoration of their relations strained over the deployment of a US Terminal High Altitude Area Defense antimissile system.

But it is questionable if Moon’s state visit to Beijing will put an end to the THAAD conflict, which has culminated in economic retaliation from China.

Chinese Foreign Minister Wang Yi reportedly said at his meeting with his South Korean counterpart Kang Kyung-wha that both sides reached some agreements to resolve the THAAD issue step-by-step. He called for South Korea to carry out the three policies that it disclosed late last month when it agreed to mend ties with China.

At that time, South Korea said it would not do three things: deploy additional THAAD systems, join the US missile defense program and form a three-nation military alliance with the US and Japan.

Wang said that he made much of the South Korean position that the provisionally deployed THAAD in Korea should not hurt the security interests of China.

He added that words must be creditworthy and that actions must produce results. In a nutshell, South Korea should keep its promise to get the US missile shield withdrawn from its territory.

On Nov. 11, Chinese President Xi Jinping, referring to the three policies, called for South Korea to show a “responsible attitude.” On Nov. 13, Chinese Premier Li Keqiang mentioned a step-by-step withdrawal of the THAAD.

These mock the South Korean government’s earlier announcement that the Oct. 31 accord to mend ties had ended the THAAD problem and that the issue would not be raised again. Now, it is dumb as an oyster about Beijing’s explicit pressure.

Criticisms of South Korea’s submissive attitude or suspicions of a dual accord with regard to the fence-mending agreement are reasonable.

Some observe that Beijing may resume economic retaliation at any time if it becomes discontent with the South Korean government’s moves.

The difference between Seoul and Beijing over whether the THAAD issue was sealed must not be obfuscated.

As follow-up measures to the fence-mending accord, Beijing reportedly demanded Seoul explain the technicalities of the system, allow China to inspect the THAAD site in Korea and build a barrier to prevent the system’s radar from monitoring China. Beijing suspects the US missile shield of spying on its territory.

South Korea attempted to explain the system, but China has refused. Inspection of the site and construction of the wall are not matters that South Korea has the right to decide on. The THAAD is US military asset installed on a US base in Korea. Beijing is asking too much.

If the two nations are sincere in putting their ties back on track, unreasonable demands must cease. They may well find other fair ways to deal with the issue.

The three policies and the issue of what to do about the system that has been deployed are grave matters concerning the national security of South Korea. The government must not try to gloss over them.

China pressures South Korea to take substantial measures on a system fielded primarily to defend US forces in Korea from North Korean missile threats. Unless the South Korean government draws a clear line between what it can do and what it cannot, the THAAD issue will remain a thorny one. It should be clear about saying no to what it cannot accept.