The Russian Navy's Bykov (Project 22160)-class corvette Vasily Bykov, one of two ships involved in the attack on Snake Island. (Michael Nitz/Naval Press Service)

Russian forces captured Zmiinyi (Snake) Island during the first day of its invasion of Ukraine, the State Border Guard Service of Ukraine confirmed on 25 February.

The Ukrainian island is located in the Black Sea near the Danube Delta, about 70 n miles from Odessa, and plays an important role in delimiting Ukrainian territorial waters.

During the confrontation with Russia on 24 February, all 13 border guards defending the island were killed, Ukrainian President Volodymyr Zelensky said in a video message on 25 February.

The Ukrainian Ministry of Defence confirmed that the attacks on the island were carried out by air and sea, with the ships involved being the Slava (Project 1164)-class cruiser Moskva and the Bykov (Project 22160)-class corvette Vasily Bykov.

Meanwhile, the Ukrainian Navy continues to defend the southwestern part of the country's Black Sea coast, Ukrainian Armed Forces confirmed on 25 February. The forces are facing simultaneous attacks by Russian forces on the bases and ports of Odessa, Yuzhny, and Ochakiv. A Turkish-owned commercial vessel, Yasa Jupiter , was hit by a bomb off the coast of Odessa on 24 February while on its way to Romania, Turkey's General Directorate of Maritime Affairs stated on its social media account.

In a video message to Mykolaiv residents on 25 February, chairman of the Mykolaiv state regional administration Vitaly Kim said the region continues to defend itself and has not surrendered. At least four soldiers were wounded in explosions at the Ochakiv naval base in Mykolaiv region on 24 February, Kim said. Ochakiv is the headquarters of the navy's 5th Brigade of Surface Ships and was envisaged to be upgraded to host NATO and allied vessels during joint exercises.

In the Sea of Azov, Russia conducted missile strikes on the coastal town of Prymorskyi Posad in the Zaporizhizhia oblast on 25 February, the State Border Guard Service of Ukraine stated on its social media account. An air defence base in Mariupol was also reportedly under Russian strikes on 24 February. Attacks have also been reported on 25 February in Berdyansk, the site of the Vostok naval base currently being constructed.

In addition to Moskva and Vasily Bykov , the Admiral Grigorovich-class Admiral Essen is also operating in the Black Sea. There are also 13 large Russian Navy landing ship tanks (LSTs) and another five smaller landing craft operating in the Black Sea region, some of which are in the Sea of Azov. In video footage posted by Ukrainian media outlet MyKerch on its VKontakte social media account on 21 February, more than 10 Russian Navy warships could be seen headed towards the Sea of Azov through the Kerch Strait. The ships include the 184th Water Area Protection Brigade's Grisha-class corvette Eisk , the Bykov-class corvette Pavel Derzhavin , the 197th Landing Ship Brigade's (Project 775)-class landing ships Tsesar Kunikov and Novocherkassk , the Alligator (Project 1171)-class landing ship Saratov , the 41st Missile Ship Brigade's Tarantul (Project 12411)-class corvette Neberezhnye Chelny , and an unidentified tug heading north through the Kerch Strait into the Sea of Azov on 21 February.

As of 15 February there are at least 19 Russian Navy ships in the Mediterranean, including the two Slava-class cruisers ( Varyag and Marshal Ustinov ), two Udaloy (Project 1155) destroyers ( Admiral Tributs and Vitse Admiral Kasatonov ), the Project 11356M frigate Admiral Grigorovich and the Admiral Gorshkov (Project 22350)-class frigate Admiral Kasatonov , a Buyan-M (Project 21631)-class corvette, two Kilo (Project 636)-class submarines (one confirmed as Krasnodar ), and other assorted vessels, including a minesweeper, an intelligence ship, tugs, and tankers.

NATO secretary general Jens Stoltenberg stated on 24 February that NATO had more than 120 allied ships “from the high north to the Mediterranean and more than 100 jets on high alert”, however, there are currently no NATO naval assets providing reinforcement in the Black Sea itself. For the past few weeks three NATO carrier strike groups (CSGs) have been operating in the Mediterranean Sea on exercises: the US Navy's Harry Truman CSG, the French Navy's Charles de Gaulle CSG, and the Italian Navy's Cavour CSG.