Turkish President Recep Tayyip Erdogan. (Bulent Kilic/AFP/Getty Images)

THE IRONY in the just-completed Turkish elections is that an amazing 87 percent of eligible voters turned out, a remarkable exercise of the ballot box, but the result is likely to set back democracy. President Recep Tayyip Erdogan’s victory means a five-year term in an executive presidency of expanded powers. How he will use those powers has been amply telegraphed by his actions in recent years, especially after the failed coup attempt of 2016, when he imprisoned or silenced his critics and attempted to neuter civil society. The strongman just got a new lease on a bigger place.

How Mr. Erdogan accomplished this opens a window on the autocrat’s handbook for the 21st century. What authoritarians have figured out is not to cancel elections, as old-fashioned dictators used to do, or fake them entirely, but rather to hold the vote and control the circumstances so tightly that no one else can win. The latest Turkish campaign was neither free nor fair. Mr. Erdogan dominated television, both state and private. By some accounts, his closest rival, Muharrem Ince, from the Republican People’s Party or CHP, got one-twelfth of the broadcast airtime on state TV as the incumbent. Mr. Erdogan put the news media into friendly hands and jailed his critics before the votes were counted, a strategy of today’s autocrats to suborn electoral politics. Mr. Erdogan managed a modest first-round victory of less than 53 percent, likely leaving him envious of Russian President Vladimir Putin’s 77 percent and Egyptian President Abdel Fatah al-Sissi’s 97 percent, both in March.

Under the new powers of the presidency, narrowly approved by referendum last year, Mr. Erdogan will have achieved near-absolute power. The post of prime minister is abolished. He will have the right to dissolve the parliament; can rule by decree; and has greater control over the judiciary. When Mr. Erdogan took office 15 years ago, many hoped he would steer Turkey toward a role as a moderate and democratic Muslim state in a sea of extremism and tumult. No more. A whole generation has no idea how Turkey looked before Mr. Erdogan. After two more terms, Turkey’s democracy could be a memory buried in the distant past.

Mr. Erdogan’s Turkey, a member of NATO, remains a prickly problem for the United States and Europe. Mr. Erdogan has been cozying up to Mr. Putin and has negotiated the purchase of sophisticated S-400 air-defense systems from Moscow that are incompatible with NATO. He should be convinced that this will endanger his quest to purchase 100 F-35 stealth fighters from the United States. At the same time, Mr. Erdogan continues to unjustly hold Christian missionary Andrew Brunson and other Americans in prison, as bargaining chips for the desired extradition of cleric Fethullah Gulen, who lives in Pennsylvania. Mr. Erdogan blames Mr. Gulen for inspiring the coup attempt; Mr. Gulen denies any role. The United States must hold firm with Mr. Erdogan against such coercive tactics. Turkey’s strategic importance is undeniable, but that can’t justify turning a blind eye to the direction it is taking.