Bosphorus
Turkish strait connecting the Black Sea to the Mediterranean via Istanbul.
Last refreshed: 12 April 2026
Can Turkey close the Bosphorus to warships?
Timeline for Bosphorus
Mentioned in: EU rejects Trump's Hormuz toll venture
Iran Conflict 2026Mentioned in: Sanctioned LNG tanker sunk off Libya
Russia-Ukraine War 2026- Who controls the Bosphorus strait?
- Turkey controls passage under the 1936 Montreux Convention, which allows commercial freedom of transit but permits Turkey to restrict military vessels and close the strait in wartime.Source: Montreux Convention text
- Why is the Bosphorus important for global trade?
- It is the sole maritime exit from the Black Sea, carrying Russian and Ukrainian grain and energy exports to global markets via the Mediterranean.Source: Lloyd's List shipping data
Background
The Bosphorus is a 31-kilometre natural strait in northwestern Turkey connecting the Black Sea to the Sea of Marmara and, via the Dardanelles, to the Mediterranean. Istanbul sits on both banks. Roughly 48,000 vessels transit annually, making it one of the world's busiest waterways and a chokepoint for Russian and Ukrainian grain and oil exports.
Turkey controls passage under the 1936 Montreux Convention, which guarantees freedom of transit for commercial vessels in peacetime but allows Turkey to restrict military traffic and close the strait entirely during wartime. Ankara invoked Montreux provisions after Russia's 2022 invasion of Ukraine, barring warships from both belligerents from transiting.
The strait's strategic significance extends beyond military transit. It is the sole maritime route for Black Sea littoral states to reach global markets. Any disruption to Bosphorus traffic affects grain, energy, and container shipping across the Mediterranean basin.
