The straits of Çanakkale and İstanbul and the Sea of Marmara, known as the Turkish Straits, together constitute a single waterway that connects the Black Sea to the Mediterranean and the rest of the world's oceans. These maritime passages have always been significant enough to constitute the subject of power struggles between major powers and has therefore been a subject of various international regulations.
The existing international accord regulating the passage though the Turkish Straits is the 1936 Montreux Convention on Straits. The Convention establishes the right to freedom of passage for all ships. It also addresses the security concerns of Turkey and other Black Sea littoral States. Turkey is empowered to supervise application of these and other rules of the Convention both in time of peace and war. The Second World War was the first major test for the Convention but it is being tested again during Russia's ongoing aggression against Ukraine. This article examines the history of the Montreux Convention and how its provisions are being applied during Russia's war with Ukraine with a focus on the closure of the straits to the warships of Russia and Ukraine, the status of trade ships, and the implementation of potential UN sanctions against Russia.