This goes back to a treaty from 1936 addressing "the long-running Straits Question over who should control the strategically vital link between the Black and Me

This goes back to a treaty from 1936 addressing "the long-running Straits Question over who should control the strategically vital link between the Black and Mediterranean Seas" [1]. [1] https://en.wikipedia.org/wiki/Montreux_Convention_Regarding_the_Regime_of_the_Straits https://en.wikipedia.org/wiki/Montreux_Convention_Regarding_...