The only American ambassador to South Korea ever to command all American forces in the Pacific and Indian Oceans has tough advice for wishful thinkers who may fantasize about a deal for reconciliation with North Korea.

Absolutely fuhgeddaboudit was the sum and substance of a retired four-star admiral, Harry Harris, as North Korea renews fire-and-brimstone threats against Seoul and Washington, claiming its enemies had sent drones over Pyongyang.

“There will be no unification of the Korean peninsula short of a catastrophic event,” says Admiral Harris, who commanded American forces in the Pacific for three years before serving as American ambassador to South Korea between 2018 and 2021. 

Harris blames the impasse flatly on the nuclear ambitions of North Korea’s leader Kim Jong-un, who has not only ruled out any contact with the South’s conservative government but is ordering destruction of all possible links with the South.

“Where there’s smoke, there’s fire,” Admiral Harris tells a gathering of the Korea Defense Veterans Association at Washington. “This fire is a nuclear fire built by Kim Jong-un. We should focus on realities to meet the threat.”

Admiral Harris’s remarks are a strong warning against activists who think there’s a chance of renewing dialogue with the North while Mr. Kim builds up his relationship with Russia, to which he’s shipping artillery shells and other munitions along with military advisers serving in Ukraine.

Admiral Harris’ choice of “catastrophic” to describe the explosion that could conceivably change the course of history in Korea coincides with the language of a warning by Mr. Kim’s often outspoken younger sister, Kim Yo-jong, as the Pyongyang press published images of what it said were drones fired by South Korea.

Citing South Korea’s “crucial provocation of infringement on sovereignty” of North Korea, Ms. Kim accused the South of “resorting to the customary practice” of attempting “to escape from responsibility” for “infiltration of drones.”

Her statement, carried by Pyongyang’s Korean Central News Agency, was assumed to have reflected the thinking of her older  brother, on whose behalf she often issues strongly worded statements. 

Mr. Kim, meanwhile, in a speech marking the 76th anniversary of the founding of the ruling Workers’ Party, inveighed in the party newspaper Rodong Sinmun against “abuse of power, bureaucratism and acts of illegally accumulating wealth” — a recognition of the corruption permeating the elite.

North Korea’s threats have escalated simultaneously with the tightening of ties with Russia, as seen at a reception hosted by Russia’s ambassador to Pyongyang. 

At the reception, North’s foreign minister, Choe Son-hui, according to KCNA, declared “the Russian army and people will surely win victory in accomplishing the sacred cause of defending the sovereign rights and security of the country.”

Emboldened by a new agreement reached with President Putin in June, Mr. Kim has ordered destruction of railroad tracks, never used other than for test runs, built by Hyundai 20 years ago in hopes of bringing about regular North-South ties.

While North Korea sends “low-tech weapons to Russia,” says Admiral Harris, “Russia is providing North Korea with satellite technology” — also vital in long-range missiles. “We have to be ready for any eventuality,” he said. “This is not the time to relax. One mistake could lead us into crisis.” 

Mr. Kim’s missiles “point in every direction,” he warns. “He’s gotten rid of every fantasy about peaceful negotiations with South Korea.”