As it tries to demonstrate its continuing ability to fight, Ukraine said it had used drones to inflict serious damage on a Russian Kilo-class submarine at a Black Sea port.

Ukraine’s domestic security service, the SBU, said Monday that it struck a Russian submarine in the Black Sea port of Novorossiysk, causing critical damage to the vessel and effectively disabling it.

Ukrainian President Volodymyr Zelenskyy said in a social media post on Sunday morning that “hundreds of thousands” of Ukrainians were without electricity.

Satellite imagery has revealed visible traces of an explosion in the port of Novorossiysk, close to a Russian Varshavyanka-class submarine. According to a report by Radio Liberty, the images taken on Tuesday,

Ukraine claims it has carried out the first successful combat strike by an underwater drone against a submarine, damaging a Russian Kilo-class boat in the Black Sea port of Novorossiysk and potentially removing a key cruise missile launch platform from the war.

Ukraine has used long-range drones to attack Russian oil platforms as it expands its strikes on the country's energy sector.

The Security Service of Ukraine reported that it had struck an Improved Kilo-class submarine at the Russian naval base at Novorossiysk. The attack was carried out with a “Sub Sea Baby” drone.

A senior Kremlin official says Russian police and the National Guard will stay on in eastern Ukraine’s Donbas even if a peace settlement ends the war.

The Kremlin has described Ukraine’s push to join NATO as one of the “root causes” of the conflict. Russia sees an expanding NATO as a major security threat. But NATO’s expansion into the Baltics and other post-Soviet states is driven by a fear that Moscow would one day invade and try to fold them back under its control—as seen in Ukraine.