Both the vessels are on a list of ships subject to sanctions imposed against Russia following its full-scale invasion of Ukraine.

Russia launched its largest barrage of drones and missiles in a month across Ukraine, killing at least three people, Ukrainian President Volodymyr Zelensky said Saturday, as a Kyiv delegation heads to the United States for fresh peace talks.

Ukrainian naval drones hit two oil tankers from Russia's so-called "shadow fleet" as they travelled through the Black Sea, Ukrainian officials have said. Footage verified by the BBC shows waterborne drones speeding through the waves into the vessels, before detonating into a ball of flame, sending black smoke into the air.

Russia launched a wave of attacks on Ukraine's capital overnight, and Ukraine attacked southern Russia, during a renewed U.S. push to end the war.

President Donald Trump says Ukraine and Russia are making progress in peace talks but called the conflict difficult to solve on Tuesday night.

The team of Ukrainian negotiators began meeting Sunday morning with Rubio, Special Envoy Steve Witkoff and Jared Kushner, President Trump's son-in-law.