What better way for North Korea to greet the American vice president than to let loose another volley of missiles?

The North Koreans have done just that, firing two short-range missiles into the waters off the east coast on Wednesday, a day before Vice President Harris is to arrive in Seoul from Japan. While there, she’s been talking to the Japanese prime minister, Fumio Kishida, about defense of the region against both China and North Korea. Analysts have been forecasting for months that the North soon will conduct its seventh nuclear test — its first since September 2017.

No one knows the North Korean strongman’s timetable, but Ms. Harris’s visit is bound to be upsetting because she’s due to go to the Demilitarized Zone between the two Koreas — a foray up to the truce village of Panmunjom 40 miles north of Seoul, where she’ll be looking across the line at North Korea. That’s where President Trump and Kim Jong-un, in their third and last summit, chatted for 40 minutes in June 2019 — a meeting that wound up raising the usual false hopes but leading to no deal on North Korea’s nukes and missiles.

The timing of Ms. Harris’s South Korean stopover is all the more portentous as American and South Korean warships churn the waters off Korea’s southeastern coast. American warplanes and helicopters are roaring off the flight deck of the carrier USS Ronald Reagan in the biggest air and naval exercise in more than five years — a show of force that North Korea has already loudly denounced as preparation for invasion.

Ms. Harris undoubtedly will also pay her respects to South Korea’s new president, Yoon Suk-yeol, promising, as American officials have been doing in advance, that Washington will “stand beside” the country against any threats by the North. She’s also sure to meet and greet America’s top commander in Korea, General Paul LaCamera, though it’s unlikely she’ll be setting foot on the Ronald Reagan.

The display of American might — including the symbolism inherent in Ms. Harris’s visit — comes as Mr. Kim aligns himself closely with Russia’s president. The bond between the two has grave implications for Korea.

With North Korea’s strongman applauding Russian aggression in Ukraine, the next question is whether President Putin in turn would support Mr. Kim’s dream of raining missiles on the South. 

Speakers at a Korea Society panel discussion in New York acknowledged the near-impossibility of moving toward negotiations with Mr. Kim as long as he’s linking his policies to Ukraine.

Mr. Kim “is watching very carefully the war in Ukraine,” a foreign policy and national security specialist with American Global Strategies, Allison Hooker, formerly with the National Security Council, said. “Denuclearization doesn’t seem like a good move for him” while “options are diminishing.”

The best defense, Ms. Hooker said, is to “return to strengthening the military posture.” The phrase may sound nice, but really means only that South Korea and the U.S. should work closely on mutual defense, as they’ve been doing since Mr. Yoon’s election. 

She added that sanctions “could be effective, if they were implemented.” Indeed, they are not. Both Russia and China are providing whatever North Korea needs for survival, including food and oil.

A senior fellow at the Korea Society, Katrin Katz, also formerly with the National Security Council, noted that the “domestic political situation in both Korea and the United States” raises the question of “how long the global alliance will last” between the two.

Mr. Yoon, she said, won by “a razor-thin margin” over his progressive foe, Lee Jae-myung, and now suffers from low approval ratings, suggesting his popular mandate to get tough with North Korea was hardly guaranteed. With pivotal U.S. congressional elections coming up next month, moreover, American focus on Korea is not necessarily a sure bet.