The opposition is demanding President Moon Jae-in sack his special security adviser Moon Chung-in, who created a stir by suggesting cutting back South Korea-US joint military exercises. The opposition has good reasons for demanding this.

First and foremost, the adviser’s argument could have a negative impact on the alliance between the two countries and the upcoming summit talks between President Moon and US President Donald Trump.

President Moon has hurriedly played down the adviser’s argument as his “personal view,” saying unequivocally that South Korea will not consider scaling down the joint military drills with the US.

But the adviser’s comment that the allies should consider scaling down the joint exercises and deployment of US strategic assets if North Korea freezes its nuclear and missile provocations deepened US suspicions about the position of the new liberal government in Seoul.

Usually, a liberal government in South Korea tries to take an excessively reconciliatory policy toward North Korea and seek to reduce its security reliance on the US. This was the cases during the Kim Dae-jung and Roh Moo-hyun administrations.

The adviser’s argument could deepen US suspicions that the Moon administration will follow in the footsteps of the previous liberal governments. This does not bode well for the summit, which should -- among other things -- coordinate an effective joint policy to end the nuclear and missile threats posed by North Korea.

Moreover, Moon’s earlier decision to suspend the deployment of a US missile shield system in South Korea, which reportedly made Trump furious, had already become one of the most contentious issues for their Washington talks.

In interviews with US media outlets, the president said the decision to deploy the anti-missile system will not be reversed, but suspicions remain in Washington.

It is against this backdrop that Cheong Wa Dae rushed to dismiss the adviser’s argument and said publicly that it warned him for doing something that is not conducive to good relations between the two allies. Adviser Moon must take responsibility for making remarks that could cause misunderstanding on the part of the US.

Another reason President Moon should sack the adviser is that both the men are mistaken and confused about the responsibility and role of presidential advisers.

What’s most troubling is that Moon Chung-in -- his official title is special adviser to the president for unification, foreign affairs and security -- insists that what he says has nothing to do with the president or the government.

He argued that he said what he had to say as a “scholar” and that he did not understand why what he said in an academic forum should make so much trouble.

He even said he does not get any payment from the government and that he does not belong to a government policy-making line. “I give advice to the president and it is up to him to take it or not,” he said, adding that his profession is professor. (He is a distinguished professor emeritus of Yonsei University). He asked the media to call him a professor, not a special adviser to the president.

Disturbingly, President Moon concurs with him. The president said in an interview that “professor Moon” is not a permanent adviser, so his relationship with professor Moon is rather “informal.”

The president also said professor Moon is an academic, and he continues to be “freely active as an academic.” Then one should ask: Why does the professor, whose relationship with the president is informal and who wants to enjoy the freedom of freely speaking as an academic, need the official title?

It would be better for both men -- and more importantly for the nation – to agree that the professor -- as he wished -- devote himself to his profession. Few would care about what he says if he does not hold the title of presidential adviser.