The Ukrainian navy said the flotilla was continuing its journey regardless. "[The Russians] shoot to kill", the press service of Ukraine's Navy said on Facebook at 20:28 local time on November 25.
Three vessels, including two small warships and a tug boat, were sailing from Ukraine's Black Sea port of Odesa to Mariupol in the Sea of Azov when they were confronted by Russian border ships in a "openly aggressive" manner, the Ukranian Navy said in a statement.
According to the Ukrainian navy, the naval vessels Berdyansk, Nikopol and Yani Kapu were carrying out a planned transfer from the port of Odessa to the port of Mariupol on the Azov Sea.
There were also unconfirmed reports that three Ukrainian ships had been captured by Russian Federation - after a day of rising tensions off the coast of Crimea. Earlier this year, the Russian government opened a 19-kilometer bridge across the strait, creating a road linking Russia's Krasnodar region with the Crimean peninsula, which was annexed by Russia from Ukraine in 2014.
Two crew members were injured.
It said one small-sized Ukrainian armored artillery boat was damaged and was "dead in the water".
The Ukrainian Foreign Ministry said in a statement that Russia's actions were a violation of the U.N. Charter and worldwide law, and pledged to "promptly inform our partners about Russia's aggressive actions".
The incident began earlier on Sunday when the Ukrainian navy claimed a Russian coast guard vessel rammed a Ukrainian navy tugboat.
The Kerch Strait is a narrow body of water nestled between Crimea and the Russian mainland. And Russia's Black Sea Fleet greatly outmatches the Ukrainian navy.
Ukraine's foreign ministry said in a statement it wanted a clear response to the incident from the global community.
Ukraine's President Petro Poroshenko has convened a military cabinet for an emergency meeting, his spokesman Svyatoslav Tsegolko wrote on Twitter.
The incident came amid a confrontation at sea between Ukrainian and Russian vessels. The statement didn't mention ramming a Ukrainian tugboat.