Try a little harder to pay attention, will ya. This was in reference to the Kerch Strait Incident which occurred in 2018, when Trump was President. The incident marked a significant escalation of the tensions in the shared Sea of Azov and first time since Russia's unrecognized annexation of Crimea 4 years earlier that Russia publicly acknowledged opening fire on Ukrainian forces. An act of aggression as defined by UN Resolution 3314 Article 3 D. - 'An attack by the armed forces of a State on the land, sea or air forces, or marine and air fleets of another State;"
On the morning of November 25, 2018 the Ukrainian Navy was conducting a planned in advance transfer of 3 vessels, a tugboat and 2 military escorts, from Odessa to Mariupol via the Kerch Strait, the only passage way to the Sea of Azov. And where Putin had built his precious bridge. As the Ukrainian vessels approached the strait they were intercepted by Russian Coast Guard vessels. One of those Russian vessels, the Don, proceeded to deliberately ram the tugboat. The Russian vessels also sought to ram the the Berdyansk and Nikipol gunboats as well, but the smaller, more agile Ukrainian ships were able to successfully out maneuver them. In the process one of the Russian vessels was accidentally rammed into by another Russian vessel. Possibly the Don. The 3 Ukrainian ships then maintained station for much of the day at the southern entrance of the strait in Russian controlled waters. In the meantime Russia place a large tanker beneath the arch of the bridge to blockade the strait. A clear violation of the 2003 agreement between Ukraine and Russia states that Ukrainian- and Russian-flagged ships, both merchant ships and state non-commercial vessels, have a right to free navigation in the Strait of Kerch and Sea of Azov, which the sides consider the internal waters of Ukraine and Russia. Russia also mobilized jets to the helicopters and a special forces team to the strait thus turning it into a full blown military operation. After several hours the Ukrainian vessels having determined they would not be allowed passage through the strait then turned south away from the entrance of the strait toward the Black Sea. This is when Russia decided to up the ante and pursued the Ukrainian vessels into the Black Sea. Eventually intercepting the Ukrainians and firing upon them, wounding several Ukrainian sailors, and afterwards proceeded to forcefully board and seize the Ukrainian vessels and their crews. Ukrainian and Russian data both confirm that the attack and seizure took place in international waters more than 12 nautical miles off the coast of Russian-occupied Crimea. The Russian action was indefensible as the Ukrainian ships were clearly heading away from the Kerch Strait when attacked.