SEOUL — The 69th anniversary of the truce in the Korean War is provoking threats from Pyongyang, sad memories in Washington, and a reminder that the truce only interrupted the fighting rather than ended the vast Cold War battle on the peninsula.

The threats come from North Korea’s leader, Kim Jong-un, whom North Korea’s press quoted Thursday as boasting that the North’s “nuclear war deterrent” can “dutifully, exactly and swiftly” destroy the South Korean government and armed forces.

Those claims are best seen as Mr. Kim’s way of responding to reports that American and South Korean military people are laying plans for a “preemptive strike” against the North’s nuclear and missile facilities.

Such plans, to be sure, are abstract, in the context of joint military exercises to be conducted next month by American and South Korean forces. That’s enough to raise tensions as South Korea’s conservative president, Yoon Suk-yeol, cooperates with Washington on a hardline policy against North Korea.

By alluding to his nukes, Mr. Kim will remind his people as well as his enemies of the North’s rationale for investing incredible resources into developing an arsenal of nukes and the missiles needed to carry them.

Mr. Kim is making the threat while observing the anniversary of what the North calls its “victory” in the Korean War on July 27, 1953. That was the date on which the Korean War armistice was signed and the demilitarized zone established for dividing North from South Korea exactly where the shooting and killing had stopped.

In Washington, a somber mood prevailed over a ceremony on the Mall in which a Wall of Remembrance was dedicated bearing the names of all who died in the war as members of American military units.

These included 36,634 American troops and another 7,175 Koreans. Known by the acronym KATUSA, for Korean Augmentation Troops to the U.S. Army, they had been under American command just like the American soldiers with whom they were fighting.