After the second US-North Korea summit collapsed in Hanoi, Vietnam, concerns are mounting that Seoul may be on a collision course with Washington over sanctions against the North.

The reason for these concerns is that the Moon Jae-in administration is seeking reconciliation with the North against the US’ position to increase pressure on the communist state.

Asked during a news briefing Thursday if the US was considering sanctions exemptions for two suspended inter-Korean economic cooperation projects -- Kumkangsan tour program and Kaesong industrial park -- a senior State Department official said “No,” without elaborating.

The flat answer indicates that there is not even a remote possibility of sanctions exemptions for the projects. It is also an effective rejection of Moon’s offer. In an address a day after the Hanoi summit, the South Korean president vowed to discuss with the US ways to resume the projects.

Despite the rejection, the Moon government expressed its intent to carry on the discussions.

“I think we need to carefully discuss this (the matter of restarting the two projects) with the US, our ally, within the framework of UN sanctions,” a high-ranking government official said after the US State Department’s news briefing.

Moon told the National Security Council on March 4 to rush to prepare for inter-Korean projects agreed upon by South and North Korea last year.

On Friday, he named Kim Yeon-chul, a pro-engagement scholar and staunch backer of Korean reconciliation, as new minister of unification. The minister-nominee had once condemned the closure of the Kaesong industrial park as “self-harm.” His nomination appears intended to smooth the way for economic cooperation with the North.

However, the atmosphere in Washington is in sharp contrast to Seoul’s moves.

Multiple news media reported citing satellite photos that North Korea could be preparing to launch a rocket in the near future. This raises doubts about Pyongyang’s commitment to denuclearize, and shows how easily the North changes its attitude to negotiations with the US.

Washington warned of new sanctions, with Trump saying he would be “very disappointed” if North Korea resumed (missile) testing.

On Capitol Hill, there is widespread and bipartisan concern that Moon’s recent moves to offer economic concessions to the regime in the North without any real commitments are undermining Washington’s leverage in dealing with Pyongyang.

Sen. Cory Gardner, chairman of the Senate Foreign Relations Subcommittee on East Asia, said lawmakers would fight for new sanctions targeting ship-to-ship transfers to North Korea.

Sens. Ted Cruz and Robert Menendez wrote to Secretary of State Mike Pompeo urging him to keep up the pressure and persuade Seoul to do the same. This is an effective warning to the Moon administration.

Two other Senators reintroduced a bipartisan bill that would impose mandatory sanctions on foreign banks and companies that facilitate illicit financial transactions for North Korea.

The Moon administration must remember that sanctions have brought the North to the negotiating table. The Hanoi summit has made it clear that the only way for North Korea to get sanctions relief is full-fledged denuclearization.

Amid signs of the North readying to launch a rocket, three US-Korea joint military exercises vanished into history. Termination of the drills will make a big hole in their combined defense posture.

Now is not the time to raise tensions with Washington and risk weakening the alliance. The Moon administration must strengthen its cooperation with the US to guard against unexpected North Korean actions.

Sanctions relief when the North has taken no substantial steps toward denuclearization amounts to acknowledging its nuclear weapons. With sanctions eased, Pyongyang will feel less tempted to negotiate over its nuclear arsenal.

Inter-Korean cooperation will not be late if it comes after denuclearization.

If the Moon administration avoids looking straight at the Washington atmosphere and persists in pursuing economic cooperation with the North, it will likely mess up its mediation for further negotiations between the US and North Korea.