TWO YEARS after its illegal annexation by Russia, the Crimean Peninsula is one of the most isolated, poor and — literally — dark places in Europe. The economy is ruined: Power lines from Ukraine were severed in November, cutting off electricity to Crimea’s 2 million people, and Russian authorities have so far managed only a partial restoration. Imports from Ukraine are banned, medicines are in short supply and the once bustling tourist trade is moribund. The only thriving industry in this severed Ukrainian province is repression: disappearances, political prosecutions and other legal and physical attacks on anyone questioning the Russian occupation.

All but a few governments still recognize Crimea as part of Ukraine. But anyone who does so in the territory itself is subject to arrest, prosecution and up to five years imprisonment. A man who flew a Ukrainian flag over his house, Vladi­mir Baluh, was convicted last month, according to Crimean human rights activists we spoke to. Other Ukrainian citizens are being prosecuted by Russian prosecutors for participation in the anti-government demonstrations that brought down the Ukrainian government in Kiev in 2014, on the basis of testimony from pro-Russian security force personnel who later took refuge on the peninsula. In gross violation of international law, a number of political suspects, including well-known filmmaker Oleg Sentsov , have been transported across the border to Russia for trial and imprisonment.

The most severe repression is reserved for Crimea’s Tatar minority, some 300,000 people, most of them Muslims, who were deported from the region by Joseph Stalin and allowed to return only in the 1980s. Three present or former top leaders of the community’s self-government organization, the Majlis, have been charged with crimes; two are in exile and the third is imprisoned. Last month, a Russian prosecutor asked a court to ban the Majlis as an extremist organization, an act that would criminalize 2,300 members of the Tatar elite. In classic KGB style, Russian authorities are establishing a new Tatar organization under their control and have launched a new Tatar television station to replace the independent one that was shut down.

Other measures are aimed at forcing Crimeans to live as Russian citizens. Young men are being drafted into the armed forces and threatened with arrest if they do not report for service. Russian passports are now needed to obtain medical care and other social services. Meanwhile, thousands of officials, security force members and other settlers have been brought into the province from Russia.

The anniversary of Russian President Vladimir Putin’s proclaimed annexation of Crimea last week prompted a few speeches at the United Nations, including by U.S. ambassador Samantha Power. “Russia’s attempted annexation of Crimea,” she said, “is not a one-time violation of Ukraine’s sovereignty, but rather represents an ongoing, continuous violation, one that persists for every day that Russia continues to occupy the peninsula.”

Ms. Power warned against getting “used to a new normal” in which that aggression is tacitly accepted. Unfortunately, much of Europe already appears headed in that direction, with pressure mounting for the lifting of European Union sanctions. Crimeans surely will continue to suffer from Mr. Putin’s invasion; ensuring that his regime also does so will require U.S. steadfastness, and some vigorous diplomacy in the coming months.