MANHATTAN—Tuesday, the White House clarified President Trump’s remarks that the United States would suspend “war games” on the Korean peninsula.

“We will be stopping the war games, which will save us a tremendous amount of money, unless and until we see the future negotiation is not going along like it should,” the president said earlier in the day in Singapore, at the press conference immediately following his historic summit with North Korean leader Kim Jong Un. “But we’ll be saving a tremendous amount of money. Plus, I think it’s very provocative.”

Hours later, after evident confusion at the Pentagon and across Washington, the White House announced the U.S. military would continue to train with South Korea’s but would no longer participate in large joint exercises.

Suspension of the exercises, however, undermines the ability of the U.S., which has treaty commitments to defend the South, to deter North Korea.

The U.S. and South Korean militaries, which operate under a combined command, engage in two sets of annual large-scale exercises. Key Resolve and Foal Eagle are held in the spring, and Ulchi Freedom Guardian takes place in late summer.

As David Maxwell, who served five tours with the U.S. Army in South Korea, told The Daily Beast, the timing of the exercises is anything but coincidental. Key Resolve and Foal Eagle coincide with the winter training cycle of the North Korean military, and Ulchi Freedom Guardian coincides with its summer cycle.

The Korean People’s Army poses its greatest threat to South Korea at the conclusion of its two training cycles. For instance, the winter cycle wraps up in March, when the ground in South Korea is still hard and sometimes frozen. That condition makes it easy for the North’s mechanized units to roll quickly through the South. Later, rice farmers in the South flood their paddies, incidentally making the terrain unfriendly for invaders from the north.

Trump’s suspension cancels this year’s Ulchi Freedom Guardian, essentially a headquarters exercise involving computer simulations. The drill usually takes place in August. By then, Maxwell notes, all or virtually all personnel moves for the year have been made. This exercise trains the Combined Forces Command headquarters and its subordinate components so that everyone, Korean and American, understands defense plans and responsibilities in event of a North Korean attack.

Cancellation of Ulchi Freedom Guardian, therefore, means personnel, either new to the peninsula or new to their posts there, will not be as well prepared as they could and should be. As Robert Collins, a longtime advisor to U.S. Forces Korea, wrote to me Tuesday, “Suspension of combined training within the South Korea-U.S. alliance will have a severe deleterious effect on alliance readiness because such training enables greater interoperability between the two militaries.”

And there could be consequences. “To stop annual exercises would undermine the readiness of American troops stationed in Korea and create more casualties in wartime,” Bruce Bechtol of Angelo State University told The Daily Beast.

Skipping Ulchi Freedom Guardian one year is tolerable. Maxwell maintains much of the training can be moved from the now-banned named exercises “to routine year-round training in a winter and summer cycle in which we still conduct the required training to sustain readiness.” Yet the large exercises are necessary in the long run if the alliance is to retain the ability to repel a North Korean attack.

And that is the reason North Korea has consistently opposed the joint drills. Trump, by saying the U.S. will not participate in them during “denuclearization” negotiations, has therefore given Pyongyang one more reason to drag out talks. No wonder North Korean media is celebrating the ending of the drills.

Trump obviously thinks that going soft on Pyongyang will win its cooperation on other matters. Unfortunately, he is buying into a notion that, in the past, has not worked with the North Koreans.

At the same time, Trump is adopting Pyongyang’s propaganda lines and language. As Bechtol, the author of the forthcoming North Korean Military Proliferation in the Middle East and Africa, says, Trump might have learned the term “war games” from his conversation with Kim on Tuesday because that is not a label the Pentagon uses for joint exercises.

Moreover, Bechtol points out that Trump is using North Korea’s slur of “provocative” for the drills. The annual exercises Trump is abandoning are provocative only to regimes that plan to invade. For those who wish to live in peace with their neighbors—that describes South Koreans—the drills are absolutely necessary to defend their way of life.

And America’s too. Trump seems to think American troops are mercenaries, that U.S. troops are in South Korea solely for the benefit of the South Koreans.

That is a mistaken view. The U.S. has business interests in South Korea, and there are about 230,000 Americans on the peninsula.

Moreover, South Korea is one of the two countries that anchor the northern end of America’s western defense perimeter. Washington policymakers, for about a century and a half, have drawn that perimeter off the coast of Asia instead of off the coast of Hawaii. American troops, in short, are in South Korea to defend the American homeland.

Since the Korean War armistice in July 1953, there has been a general peace in North Asia. One reason for the quiet in the troubled region is that the militaries of the United States of America and the Republic of Korea have drilled together.

Those drills, unfortunately, will no longer take place.