Kerch Strait incident

The Kerch Strait incident was an international incident that occurred on 25 November 2018 in the Kerch Strait, during which the Russian Federal Security Service (FSB) coast guard fired upon and captured three Ukrainian Navy vessels after they attempted to transit from the Black Sea into the Sea of Azov through the strait on their way to the port of Mariupol. It was the first time that Russian forces had openly engaged Ukrainian forces during the Russo-Ukrainian War.

In 2014, Russia had annexed the nearby Crimean Peninsula, which is predominantly internationally recognised as Ukrainian territory. It later constructed the Crimean Bridge across the strait. Under a 2003 treaty, the strait and the Azov Sea are intended to be the shared territorial waters of both countries, and freely accessible. Russia, in turn, insists that, while the 2003 treaty remains legally valid, Ukrainian ships must ask for permission before entering Russian waters along the perimeter of Crimea as any transnational water crossing, as regulated by the Law of the Sea Treaty. The annexation of Crimea by Russia is recognized only by Russia and a small number of its allies, therefore Ukraine holds that the invocation of an international treaty with regard to Crimean waters is illegitimate.

As the flotilla, which consisted of two gunboats and a tugboat, approached the Kerch Strait, the Russian coast guard said they repeatedly asked the Ukrainian vessels to leave what they referred to as "Russian territorial waters". They said that the vessels had not followed the formal procedure for passage through the strait, that the Ukrainian ships had been manoeuvring dangerously, and that they were not responding to radio communications. Ukraine said that it had given advance notice to the Russians that the vessels would be moving through the strait, that the ships had made radio contact with the Russians, but received no response, and cited the 2003 treaty against the assertion that the ships had entered Russian territorial waters.