A Ukrainian drone attack on the Russian city of Nizhnekamsk killed 12 people and injured 39 others on Monday, authorities in Russia’s Tatarstan region said.

Tatarstan’s head Rustam Minnikhanov’s press service said the city was hit by a “massive” drone attack in the morning, targeting both industrial and civilian facilities.

Ukraine has intensified attacks on Russian oil facilities with long-range drones in recent months. The strikes have disrupted fuel supplies, reduced Russia’s refining capacity and increased public concern over the impact of the war.

Ukrainian President Volodymyr Zelenskyy has said the campaign is aimed at pressuring Russian President Vladimir Putin to enter negotiations and end the more than four-year-old invasion of Ukraine.

Nizhnekamsk, located about 1,200 kilometers (750 miles) east of the Ukrainian border, has a population of around 240,000. It is a major oil-refining and petrochemical center, hosting two refineries and a petrochemical plant.

“We do deliver entirely justified responses, and every Russian strike will be met with our response,” Zelenskyy said on social media late Sunday.

“Russia’s war will be felt more and more at their own home – in Russia,” he said, adding that the conflict continues because of “Russia’s unwillingness to end this war.”