North Korean missile shots and the American and South Korean military exercises provide a stark reminder of the dangers facing the Korean peninsula. 

The American and South Korean commands had been expected to postpone the latest war games after Americans and Koreans canceled cultural events, put off conferences, and focused on services and memorials for the victims of the recent tragedy at Itaewon. The military decision, however, was that their show must go on in defiance of North Korean threats, not to mention missile and artillery fire. 

It was all part of the need to “maintain a thorough readiness posture against various threats,” the chairman of South Korea’s joint general staff, General Kim Seung-kyum, said as he visited Osan Air Base, 40 miles south of Seoul, where many of the planes are based.  

Living up to their warnings, the communists launched a barrage of more than 20 missiles and upward of 100 cannon shots after promising “powerful follow-up measures” as more than 200 American and South Korean warplanes took to the skies in their largest aerial exercises in years. One of the North Korean missiles landed in waters near a small island south of what’s called the Northern Limit Line beneath which North Korean ships are banned by the South.

North Korea does not recognize the NLL but had never previously fired a missile that far south. The shot set off air raid alarms on the island, the South fired a few more missiles of its own off the coast, and the South’s presidential office reported  Yoon Suk-yeol had ordered “strict measures” needed “to ensure North Korea pays a clear price for its provocation.” There were no details, but Mr. Yoon vowed the South would do what was needed “to protect the people’s lives and safety” against any “additional and high-intensity provocations.”

American and South Korean officers agreed nothing should stop them testing defenses against a torrent of rising invective from North Korea’s leader, Kim Jong-un. He’s ordered dozens of missile tests this year and is believed to be preparing for the North’s seventh nuclear test, its first since September 2017.

Korean observers attributed the urgency of the exercises to the culture of “pali, pali” — “hurry, hurry” —that characterizes the breakneck speed at which the Korean economy has exploded along with the spread of Korean art and entertainment, as seen in the enormous global popularity of K-pop.

Incredibly, the psychology behind the war games parallels the outlook that gave rise to the Halloween horror in Itaewon. “It’s the ‘pali-pali’ mentality,” a middle-aged Korean office worker who viewed the unfolding tragedy on television from his nearby apartment, Park Ki-bum, said. “They were madly pushing one another. It’s in the genes.”

The same psychology explains the dramatic reversal from the intensely soft-line policy of the previous liberal president, Moon Jae-in, to the equally hard line of the conservative Mr. Yoon. After five years in which Mr. Moon did away with anything beyond computer games with the Americans, Mr. Yoon has totally reversed that policy, urgently standing up to Mr. Kim with the South’s American ally.  

Messrs. Yoon and Kim have defended their policies with a fierceness that shows the deep divisions within Korean society and the depth of insoluble differences between South and North. Mr. Kim, of course, stands fast against American and South Korean demands, refusing to give up his nukes and missiles with the ferocity of his own unyielding authority.

In the same “pali-pali” spirit, American and South Korean F35s are at the vanguard of the ongoing exercises that also feature B-1 and B-52 bombers based in Guam and elsewhere that an Australian KC-30 tanker plane is tasked with refueling. They’re complemented by soldiers and marines on the ground in a five-day fist-wielding display called Vigilant Storm.

The exercise deepens the confrontation, fulfilling Mr. Yoon’s promise to reverse the appeasement policies of his predecessor, who dreamed the impossible dream of a deal with the North. America’s Seventh Air Force, based at Osan, promised the war games would “strengthen the operational and tactical capabilities of combined air operations.”

South Korea’s General Kim said the exercises were needed  to be able “to thoroughly punish the enemy” in case North Korea’s Mr. Kim goes beyond missile and artillery tests — putting North and South on a collision course posing dangers far worse than last weekend’s deadly pile-up of bodies at Itaewon.