Ukrainian drones struck 20 Russian vessels in the Black Sea overnight Wednesday, including 17 oil tankers, two gas carriers and one tugboat, said Robert Brovdi, commander of Ukraine's Unmanned Systems Forces. Brovdi, who uses the call sign 'Madyar,' claimed all the ships are part of Russia's so-called shadow fleet used to transport oil in circumvention of international sanctions.

The attack was part of an operation Brovdi called 'MoLoChKa,' an acronym he said stands for 'Moscow Will Fall Through Crimea.' The operation aims to cut off the annexed Crimean Peninsula from supplies from mainland Russia. Brovdi said he would later publish an official report with video.

Ukrainian monitoring channel Supernova+ said it could confirm damage to at least seven tankers and other vessels. The channel published footage from coastal surveillance cameras showing flashes at sea. The 412th separate unmanned systems brigade 'Nemesis' took part in the attacks, according to the channel.

Over the past 10 days, Ukrainian drones also struck 116 Russian ships in the Sea of Azov, Brovdi said. In response, Russia temporarily halted shipping along the Azov-Don Sea Canal and stopped accepting requests for passage through the Kerch Strait.

After the strikes, Russian vessel activity in the Sea of Azov dropped sharply, according to the U.S.-based Institute for the Study of War (ISW). The number of ships with active AIS transponders in the area fell by 55% — from 267 in late June to 120 by July 11. Near Kerch, the number dropped by 75% — from 37 to 9. Some tankers and other vessels moved into the Black Sea, while others were sent for repairs or storage.

On Tuesday, the Rostov region's transport and agriculture ministries said they were seeking alternative routes for exporters as the harvest campaign began. Analysts noted that the shipping halt could deprive Russia of up to 20% of its grain exports.

Earlier, Russian Foreign Minister Sergei Lavrov responded to the drone attacks on ships. At a press conference, he called Kyiv's actions terrorism. 'This is no longer even piracy — what the Ukrainian regime is doing. Pirates at least rob and take for themselves. But here it's neither for themselves nor for others — just to cause damage, to intimidate. Pure terrorism,' Lavrov said. Brovdi replied in his Telegram channel: 'No piracy, Lavrov — just business. Your bloody business.'