WATCH Russian FSB Ships Pursue Ukrainian Vessels in Kerch Strait

Russian defence ministry TV channel Zvezda has published footage showing a Russian border guard ship converging on and escorting Ukrainian Navy ships as they approach the Kerch Strait.

Earlier, Sputnik reported that at around 7 am Moscow time, three Ukrainian Navy vessels illegally crossed the maritime border with Russia and proceeded to move through the Kerch Strait from the Black Sea. Two more Ukrainian vessels were later reported to be heading to the area from the Sea of Azov.

Russia deployed border guard and military patrol ships and military aircraft in the area to contain the situation, with footage earlier emerging of Su-25 attack aircraft flying in the vicinity of the recently-built Crimean Bridge spanning the Strait. Russian Navy vessels and cargo ships have blocked access to the Strait to prevent unauthorized entry or exit in connection with Sunday's incident.

The situation in the Sea of Azov and around the Kerch Strait was aggravated in March, after Ukraine detained a fishing trawler with ten Russian nationals onboard, and then again in August, when a Russian sailor was arrested in the Ukrainian port of Kherson. Moscow has described Ukraine's actions as "maritime terrorism," and strengthened its maritime border in the Sea of Azov.