In a move to assert its authority, Russia closed the Strait of Kerch which links the Azov Sea with the rest of the Black Sea and a naval confrontation with Ukraine ensued. Three Ukrainian naval vessels were involved in clashes with Russia in an unprecedented incident that will raise tensions between Moscow and Kiev.Sergei Aksyonov, the head of Crimea, which was annexed by Russia from Ukraine in 2014, claimed Western powers were behind Ukrainian naval moves. He asserted that “Ukrainian warships illegally crossed Russia’s borders.” Three Ukrainian ships set off in the morning to pass the Kerch Strait and reach Mariupol, a port on the Azov Sea. Russia claimed the ships were entering Russia’s territorial waters and carrying out “dangerous” actions.From Ukraine’s perspective, the Russian annexation of Crimea is not recognized and Ukraine should be able to sail ships through the strait to its ports, otherwise Russia could simply close off the Azov Sea whenever it likes. An article by the Jamestown Foundation in early November claimed that Russia was carrying out “purposefully time-consuming inspections on merchant vessels traveling to and from Ukraine’s Azov Sea ports.” In six months, 683 vessels had been boarded and Ukraine claimed it was losing millions of dollars.The tree Ukrainian ships, named the Berdyansk, Nikopol and Yani Kapu, were involved in the clashes. The first two ships were relatively modern Gurza class artillery patrol boats, which have two main guns and a grenade launcher. The third ship was a Ukrainian tugboat. According to Kyiv Post, the tugboat was rammed by the Russians and all three ships were immobilized after an exchange of fire and taken over by Russian forces. This is a humiliating defeat at sea for Ukraine.According to local reports, Ukraine has raised the alert level of its forces in Donetsk, a front line where Ukraine is fighting Russian-backed separatists but where there is supposed to be a ceasefire. Video showed a Russian coastguard vessel, towering over the tug boat, before ramming it. Russia also flew two Su-24 bombers over a bridge linking Crimea with the mainland.All of this is designed as a show of force. In Donestk there is an existing conflict, which began when the Russian-backed Ukrainian President Viktor Yanukovych fled Kiev in 2014 and separatists took up arms in the east. Ukraine and Russia have been fighting a kind of proxy war since then in Donetsk, with European powers mostly supporting Ukraine. It is seen as part of Russia’s larger grand strategy of asserting itself in the Caucuses, the Balkans, and in Syria and the Middle East. This has often included political, economic and military muscle working together. In Crimea, Russia wants to send a message to Europe that this is Russian territory and that Ukraine’s small navy won’t be able to navigate the Kerch Strait without Moscow’s approval.Russia’s Black Sea fleet is based at Sevastopol and this is a key strategic interest for Moscow. The clashes over the straits come the same day Russian bombers struck Syrian rebels that it accused of firing mortars on Aleppo on Saturday. In both cases, Russia’s military might is being illustrated, and Moscow will not back down either from its support for the Syrian regime or over Crimea. This will be a test for Ukraine, and also for its supporters in Europe and in Washington. Rights to navigation is a key concept, but whether Ukraine will force the straits issue again remains to be seen, especially after having three of its ships detained.Ukraine has now asked the UN Security Council to meet and the EU has called for freedom of passage of the Kerch Strait, potentially leading to a crisis between the Western powers and Russia.