Online Desk: Russian President Vladimir Putin is poised to extend nearly a quarter century of rule for six more years on Sunday after wrapping up an election that gave voters no real alternatives to an autocrat who has ruthlessly cracked down on dissent.

The three-day election that began Friday has taken place in a tightly controlled environment where no public criticism of Putin or his war in Ukraine is allowed. Putin’s fiercest political foe, Alexei Navalny, died in an Arctic prison last month, and other critics are either in jail or in exile.

The 71-year-old Russian leader faces three token rivals from Kremlin-friendly parties who have refrained from any criticism of his 24-year rule or his full-scale invasion of Ukraine two years ago. Putin has boasted of Russian battlefield successes in the run-up to the vote, but a massive Ukrainian drone attack across Russia early Sunday sent a reminder of challenges faced by Moscow.

The Russian Defense Ministry reported downing 35 Ukrainian drones overnight, including four near the Russian capital. Moscow Mayor Sergei Sobyanin said there were no casualties or damage.

Russia’s wartime economy has proven resilient, expanding despite bruising Western sanctions. The Russian defense industry has served as a key growth engine, working around the clock to churn out missiles, tanks and ammunition.

Russia’s scattered opposition has urged those unhappy with Putin or the war to express their protest by coming to the polls at noon on Sunday. The strategy was endorsed by Navalny not long before his death.

Voting is taking place at polling stations across the vast country’s 11 time zones, in illegally annexed regions of Ukraine, and online. Despite tight controls, at least a half-dozen cases of vandalism at polling stations were reported Friday and Saturday.

A 50-year-old university professor was imprisoned Saturday for 15 days after she tried to throw green liquid into a ballot box in the Urals city of Ekaterinburg, local news site Ura.ru reported. In Podolsk, a town close to Moscow, a woman was fined 30,000 rubles ($342) and charged with “discrediting the Russian army” after spoiling her ballot with an unspecified message, according to OVD-Info, a police monitoring group.

Ahead of the election, Putin cast his war in Ukraine, now in its third year, as a life-or-death battle against the West seeking to break up Russia.

Putin has boasted about recent gains in Ukraine, where Russian troops have made slow advances relying on their edge in firepower. Ukraine has fought back by intensifying cross-border shelling and raids, and by launching drone strikes deep inside Russia.

Air raid sirens sounded multiple times Saturday in the Russian border city of Belgorod, where two people were killed by Ukrainian shelling, regional Gov. Vyacheslav Gladkov said. Russia’s Defense Ministry said it had thwarted attempts to enter the country by “Ukrainian sabotage and reconnaissance groups,” following claims by Ukraine-based Russian opponents of the Kremlin last week that they had made an armed incursion into the Belgorod and Kursk regions.

Western leaders have derided the election as a travesty of democracy.

Beyond the lack of options for voters, the possibilities for independent monitoring are very limited. No significant international observers were present. Only registered, Kremlin-approved candidates, or state-backed advisory bodies, can assign observers to polling stations, decreasing the likelihood of independent watchdogs.