For the Soviet Union, the Turkish Straits could not have been more important. Since ancient times, the narrow bodies of water that make up the Bosphorus and the Dardanelles via the Sea of Marmara held enormous strategic importance – both militarily and in terms of trade. The only way the Soviet navy could get from its Black Sea ports to the Mediterranean and the wider world was through the straits.
In 1936, the Soviet Union, along with several other regional and world powers, signed the Montreux Convention. It agreed that only ships from countries bordering the Black Sea could use the straits and it was up to neutral Turkey to police it. This, however, wasn’t enough of a guarantee.
With the Second World War out of the way, Soviet deputy premier Lavrentiy Beria declared that a swathe of eastern Turkey close to the Black Sea belonged to Georgia, then part of the Soviet Union. It had been stolen, he said, by the Turks during the days of the Ottoman Empire. Moscow also complained that ships not from the Black Sea had been allowed to pass through the straits in violation of the convention.
For the Americans, this confirmed their worst fears of Soviet expansionism. President Truman decided that the Soviet Union had to be contained, leading to the Truman Doctrine. In April 1946, the huge American battleship USS Missouri arrived in the straits, conveniently bearing the ashes of the deceased Turkish ambassador. The Soviet Union smelt a rat.
The crisis reached a head on 7 August 1946, when the Soviet Union handed Turkey a note stating that it had breached the Montreux Convention and a new treaty was needed. A Soviet military build-up followed.
Fearing Soviet designs on the straits, Britain and the United States declared their support for Turkey and a naval taskforce was dispatched to the region. Moscow backed down, and under protest, withdrew its demands for a renegotiation of the convention.
Turkey abandoned its policy of neutrality in accepting aid from the United States, and in 1952, joined Nato. With the death of Joseph Stalin the following year, the Soviet Union dropped its territorial claims and relations with Turkey began to thaw.