South Korea, which fought against Vietnamese communists during the 1960-1975 Vietnam War, is accused of killing many civilians in Vietnam while carrying out operations during the war. About 5,000 South Korean soldiers died in the war.

It remains a sensitive issue for the two countries despite their expanded exchanges in diverse areas for the past 25 years since they built diplomatic ties.

The issue was stirred up anew when South Korean President Moon Jae-in said in his speech on June 6 marking Memorial Day that South Korea's economy got a boost from the country's participation in the Vietnam War.

The Vietnamese foreign ministry voiced its displeasure with the president's comments, calling for the Seoul government to refrain from making comments that could hurt the feelings of its people.

In his video message for a joint event between the two counties in Ho Chi Minh last month, Moon said that South Korea has "debt in mind" to Vietnam, apparently pointing to the wound that the Vietnamese people suffer from the horrible memories related to the war.

  "Bygones are just bygones. I think this applies not just to South Korea but other countries as well," Dr. To Anh Tuan said. "That is to say that let's know what happened but leave it behind to move forward, not talking about forgetting it."

He emphasized that the two countries have good relations that have become "friendlier than ever" but expressed hope that the bilateral ties will further deepen in many areas going forward.

As for mounting tension after North Korea's recent test of what it claims to be an intercontinental ballistic missile, he voiced grave concern and called for "restraints" from countries involved. He also urged them to explore peaceful measures to resolve the current stalemate.

On Wednesday, North Korea said that it has successfully tested a new ICBM capable of hitting anywhere in the US and declared that the launch marks the completion of its nuclear armament.

"It's very concerning to see the situations unfolding on the Korean Peninsula," he said. "The two Koreas should restrain from excessive acts and (countries involved) should restrain from any provocative behaviors."

  "In particular, all possible systems and mechanisms including talks should be employed, and I wish countries to strictly carry out the resolutions adopted by the UN Security Council as they are," he added. (Yonhap)