North Korea, decried as “flaunting” its nuclear capabilities ahead of America’s election, has just test-fired its longest-range intercontinental ballistic missile, which is capable of striking here, and Pyongyang is reportedly prepped and primed for its seventh nuclear test.

The North’s leader, Kim Jong-un, justifying the ICBM test while pouring North Korean troops into Ukraine, said the North had to “round off our nuclear forces’ response posture” while “bolstering up its nuclear forces” — a strong hint the North was ready to test a nuclear warhead for the first time in more than seven years. 

Pyongyang’s Korean Central News Agency quoted Mr. Kim as calling “the test-fire” of the ICBM “an appropriate military action” in “an indispensable process of constantly developing our state’s strategic attack forces.” 

He gave no details, but South Korea’s Yonhap News said the missile soared a record 4,350 miles skyward before plopping down in waters between North Korea and Japan — on a flat line easily long enough to carry a nuclear warhead to targets anywhere in North America. 

South Korea’s joint chiefs of staff said the launch of the missile was apparently “aimed at flaunting” the North’s “nuclear capabilities ahead of the U.S. presidential election next week,” but Mr. Kim gave no reason for the timing.

Nor did he say, as reported by South Korea’s military, that the missile was powered by solid fuel — much faster to launch than liquid-fueled missiles that have to sit on the launchpad, visible from satellites, while gassing up.

 Also alarming, North Korea appears to be hovering on the brink of testing a nuclear warhead in defiance of warnings from America and South Korea — and apparently advice from Communist China. 

South Korea’s defense minister, Kim Yong-hyun, at Washington for talks with Defense Secretary Austin, said that North Korea might conduct the test around the time of the American elections. 

Whether the election is a factor was not clear, but Mr. Kim obviously wants to show off his strength while Washington and its allies denounce the entry of several thousand North Korean troops supporting the Russians in Ukraine.

South Korea intelligence officials reported preparations were “complete” for conducting the test at Pyunggye-ri in the nation’s remote, mountainous northeast.

That’s where the North has conducted six tests since Kim Jong-un’s father, Kim Jong-il, who died in 2011, ordered the North’s first two tests in October 2006 and May 2009.  

The younger Mr. Kim has ordered four more tests — the last, that of a hydrogen bomb that reportedly destroyed much of a mountain in which it was conducted, killing 200 people, in September 2017. 

Veteran analysts, including the noted Korean analyst at the Center for Strategic and International Studies, Victor Cha, and a famous Russian professor at Seoul’s Kookmin University, Andrei Lankov, have both told me for sure North Korea would conduct a seventh nuclear test. 

So far, however, China, the source of the North’s oil and half its food, is believed to have dissuaded Mr. Kim from ordering more tests for fear of fallout drifting over Chinese territory — and complicating China’s relations with South Korea, a leading trading partner and source of investment. 

Mr. Kim, however, is bursting with new confidence fostered by his ever-growing ties with President Putin, with whom he signed a strong mutual defense pact in Pyongyang in September. 

While Russian delegations stream into Pyongyang for talks and events ranging from culture to climate to weapons, he’s evidently counting on the Russians for vast quantities of aid, including the technology that may have gone into his latest ICBM. 

Mr. Austin and Mr. Kim both issued strong formal denunciations of North Korea’s new role in Ukraine, where it’s sending up to 12,000 troops.  It was up to America’s deputy ambassador to the United Nations, Robert Wood, to come out with a far more colorful, pointed, warning.

Should North Korean troops enter Ukraine, “they will surely return in body bags,” said Mr. Wood at the UN Security Council, addressing the Chinese, Russian and North Korean ambassadors, among others.  

Mr. Kim, he advised, should “think twice about engaging in such reckless endangered behavior.”