President Zelensky, in a new interview with French television, says that “retaking Crimea has begun in people’s minds.” This puts the Ukrainian leader in the crosscurrents of a growing chorus who are of a mind that action on the Russian-occupied peninsula could be a tripwire for broader conflict. “The operation itself has not started yet,” Mr. Zelensky tells the TF1 and LCI networks, but “when it does, you’ll definitely hear about it.”

In the months since Russia’s February invasion of Ukraine, Russian air bases situated on the strategic Crimean peninsula have periodically come under Ukrainian attack. Last month Ukrainian forces blew up part of the Kerch bridge, which connects Crimea to the Russian mainland. The Russians repaired it expeditiously, though, and President Putin drove across it in a Mercedes. 

In doing so, one point that Mr. Putin was making was subtle: Moscow sees the peninsula as part of Russia. More than three-quarters of its residents speak Russian as a native language, and Sevastopol was the historic headquarters of Russia’s Black Sea fleet. So Mr. Putin is expected to fight for what he illegally seized in 2014. The language of some foreign policy heavyweights has started to reflect this, case in point Boris Johnson.

Writing in the Wall Street Journal earlier this month, the former British prime minister insisted that “Russian forces must be pushed back to the de facto boundary of Feb. 24.” Unwittingly or not, his pointing to February 24 is at odds with Ukraine’s stated aspiration of regaining its territorial integrity in whole, as it stood prior to Russia’s invasion of Crimea in 2014.

That Crimea represents a tricky acquisition for Kyiv, albeit of a stolen good, was echoed by an analysis in Foreign Affairs about why Ukraine “should not rush” to retake the peninsula. For Henry Kissinger, writing in the Spectator, Crimea “could be the subject of a negotiation after a ceasefire.” He reckons that Russia’s “historical role should not be degraded” and that the country’s “military setbacks have not eliminated its global nuclear reach, enabling it to threaten escalation in Ukraine.”

Mr. Zelensky does not share that sentiment, and appears to believe that any move by Mr. Putin to deploy nuclear weapons would occur regardless of Ukraine’s stance on Crimea. “If Putin wants to use nuclear weapons, he will use them. Just as he promised Macron, Merkel — everyone — that there would be no full-scale invasion of Ukraine,” Mr. Zelensky told French viewers. “You simply cannot trust people who say something but act as they personally decided.”

“Hence, the use of any weapons depends only on the strength of Ukraine’s unity with Europe, the United States, the entire world,” the Ukrainian leader added. While there is no indication that Mr. Zelensky is in a rush to attempt to recapture the peninsula, the August attacks on air base targets there and the Kerch bridge explosion indicate a diminishing hesitation to roll the dice.

What the Kremlin might do to hold on to its prized Ukrainian possession, especially in the absence of any ceasefire, is a riddle. Moscow, though, seems to be girding for any eventuality. Recently, Russians have been building trenches. 

According to a press statement from the Ukrainian defense ministry’s intelligence directorate, reconnaissance shows that “Russians in occupied Crimea are trying to further strengthen the coastline, fearing the landing of Ukrainian troops: In particular, a network of minefields and trenches and trenches is being equipped along the coast near the village of Molochnoye,” which is almost due north of Sevastopol. 

Those defensive efforts may be for naught. Ukrainska Pravda reported that the secretary of Ukraine’s national security and defense council, Oleksiy Danilov, said that the trenches “will definitely not help them,” adding: “This is our land and it must be returned home.”

When and if, nobody knows. Will Ukraine, emboldened by successful counter-offensives at Kharkiv, Kherson, and elsewhere, go all out to get Crimea back, and if so will President Biden throw cold water in Kyiv’s direction? It has happened before. The New York Times reported that last April, American officials tried to prevent Ukraine from killing a high-ranking Russian general, Valery Gerasimov, who had been planning to visit Russia’s frontlines. 

Ukrainian forces did not succeed in taking out Mr. Gerasimov, but it was not for lack of trying; several Russians were reportedly killed in a strike, which the general escaped. With the war machine grinding on, Russian-occupied Crimea may be calm for now, but there can be no doubt the storm clouds are gathering.