• A Ukrainian security source said naval drones attacked and damaged an oil tanker on Wednesday.

• The tanker was part of Russia's "shadow fleet," which is used to move oil despite sanctions.

• Ukraine has attacked three of these ships in a matter of days as it targets Russia's energy sector.

Ukrainian forces used naval drones packed with explosives to attack an oil tanker identified as part of Russia's "shadow fleet" in the Black Sea on Wednesday, a security source told Business Insider.

The naval drone strike on the tanker, Dashan, marks the third such attack in less than two weeks as Ukraine ramps up its long-range strike campaign against Russia's energy sector, increasingly gunning for ships at sea in addition to land-based oil facilities.

Sea Baby naval drones hit the tanker and caused "critical damage" to the vessel, with early indications indicating that the strike completely disabled the vessel, the source in the Security Service of Ukraine, the country's main internal security agency, revealed on Wednesday.

The SBU source, only authorized to speak anonymously to discuss sensitive military developments, said the Dashan was flying the Comoros flag and moving through Ukraine's exclusive economic zone in the direction of Novorossiysk, a Russian port city and major oil terminal.

Publicly available ship-tracking data last showed the Dashan in the middle of the Black Sea.

The tanker was sailing at maximum speed with its transponder turned off, the security source said. They added that the attack was carried out in cooperation with the Ukrainian navy and shared footage captured by the Sea Baby drones showing multiple hits on the ship.

Several Western countries and the European Union have sanctioned the $30 million tanker, which has been used for Russian oil exports and is known to sail with its transponder switched off, Ukraine's HUR military intelligence agency said.

Business Insider could not independently verify the extent of the damage. Russia's defense ministry and its embassy in the US did not immediately respond to a request for comment.

The attack on Wednesday appears to mark the third time in the last two weeks that Ukraine has disabled a tanker belonging to the "shadow fleet." In late November, the SBU used naval drones to strike and damage two vessels before they loaded at Novorossiysk.

The "shadow fleet" is a collection of hundreds of vessels that Moscow uses to transport oil and circumvent sanctions on its energy exports, a major source of revenue. Ukrainian President Volodymyr Zelenskyy has repeatedly urged Kyiv's international partners to do more to prevent the ships from operating.

"The SBU continues to take active measures to reduce the receipt of petrodollars to the budget of the Russian Federation," the security source said on Wednesday, according to a translation of their remarks shared with Business Insider.

Ukraine has been stepping up its attacks against the Russian energy sector, the revenue from which fuels its war efforts, in recent months. Kyiv has used long-range drones to strike oil refineries and other facilities and infrastructure across the country.

The three tanker attacks appear to reflect a new shift for Ukraine — one that now increasingly attacks ships at sea rather than just land targets.

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