The United Nations Security Council discussed the implementation and enforcement of UN sanctions on North Korea in a special session the day before President Moon Jae-in arrived in Pyongyang on Tuesday for his summit with Kim Jong-un.

The US had called the session in response to what it says are efforts by “some members” to “undermine and obstruct” sanctions against the North.

An interim report, prepared by an independent UN panel that monitors sanctions compliance, was submitted to the UNSC last week after being blocked by Russia in August. While the report was submitted to the council, it is a version that has been altered under pressure from Russia, according to US Ambassador to the UN Nikki Haley.

She accused Russia of pressuring the panel to alter the report, which included sanctions violations implicating Russian actors and that the panel should release the original report, which cited “a massive increase in illicit ship-to-ship transfers of petroleum products” for North Korea in violation of UN sanctions. It said some products were allegedly off-loaded from Russian ships.

The initial report has not been disclosed, but according to news media, North Korea has been caught selling weapons to Syria, Yemen, Libya and other conflict zones around the world. Chinese firms bought iron ore, steel and other goods from North Korea.

Washington will reportedly strengthen sea surveillance jointly with its allies.

But the wind from Seoul is different from that from Washington. Though under the most direct nuclear threat from North Korea, the South seems to be accelerating appeasement with Pyongyang, fanning concern and suspicion in the US.

South Korean firms were found to have imported North Korean coal disguised as being of Russian origin, effectively violating UN sanctions and arousing concern that their government is not doing enough to enforce them.

The South also tried to send a train through the demilitarized zone to the North to test the North Korean track of a disconnected inter-Korean railway, only to be blocked by the UN Command, which denied Seoul’s application to cross the zone. The UN Command reportedly rejected the application because of the diesel the South Korean train planned to carry. Diesel supply to North Korea is restricted by UN sanctions.

The government opened an inter-Korean liaison office in Gaeseong, North Korea, despite US concern that it would be a breach of sanctions.

Moon may be envisioning denuclearizing North Korea by improving inter-Korean relations through economic projects, but such vision will strengthen North Korea’s position and impair sanctions unless it denuclearizes first.

The US has made a point of sanctions compliance each time South Korea has tried conciliatory gestures to the North.

US Secretary of State Mike Pompeo said Friday after the US accused Russia of altering the report that the enforcement of UN sanctions on North Korea was critical to the denuclearization of the Korean Peninsula. It is also a message South Korea must keep in mind.

The Moon government would be ill-advised to believe Kim will be motivated to denuclearize his country if he tries to improve inter-Korean ties through economic projects and military steps to ease tension.

It needs to recall what brought Kim to the negotiating table in the first place. Sanctions were the only leverage that made Kim realize he has no other option but to denuclearize.

However, if the North is left poking bigger and bigger holes in sanctions, aided and abetted by China and Russia, denuclearization will not come. Probably, that is what Kim really wants: A nuclear state like India or Pakistan. A North Korea economically far better off than now, but with his grip on power intact.

It is South Korea that should want airtight UN sanctions the most. And yet, the Moon administration seems very eager to do what it can if sanctions are eased or lifted. When South Korea behaves this way, how can it make demands that the US, its staunchest ally, persuade China and Russia to pressure North Korea?

Sanctions must be the first and last doors to denuclearization. If sanctions lose their teeth, efforts so far to denuclearize the North will end up as an exercise in futility. Inter-Korean relations are important, but the Moon administration must not forget sanctions are key to denuking the North.