The strategic role of Istanbul's Bosphorus in the Ukraine crisis

A Russian kilo class submarine gliding through Istanbul's Bosphorus waterway en route to the Black Sea recently provided an early morning spectacle to city commuters crossing the strait of water that divides Turkey's largest city.

A Russian kilo class submarine ALEXANDER NEMENOV / AFP

Such demonstrations of naval prowess have become common in Istanbul. As tensions rise in Ukraine, Russian and NATO warships are increasingly using the Bosphorus waterway, the only access into the Black Sea from the open waters of the Mediterranean. 

The importance of the Bosphorus

The strategic importance of the Bosphorus in the Ukraine crisis is forcing closer scrutiny of the  1936 Convention administered by Turkey which governs naval access to the Black Sea.

Russia is deploying warships from its Northern fleet to the Black Sea, while several French naval vessels are set to pass through the Bosphorus later this month. But access by non-Black Sea countries is strictly controlled by the 1936 Montreux convention, explained Mithat Rende, a retired Turkish Ambassador, an expert on maritime affairs.

"Those who are not riparian states have to limit their presence (in the Black Sea), to 45,000 metric tonnes (total ship tonnage). With a maximum of 15 vessels for a period of 21 days, and they have also to notify Turkey, giving the time and date of the passage," said Rende.

The Montreux Convention is of historical importance for Turkey as it restored Turkish sovereignty and control to the network of internal waterways linking the Black Sea to the open sea. But Mustafa Aydin, a professor of international relations at Istanbul's Kadir Has University, warns that Turkey's role as Black Sea gatekeeper put it in a difficult position with its NATO partners at times of high tensions with Russia. 

"We have seen this during the Russian Georgian war in 2008. The United States and other NATO allies tried to bring more ships into the region. Initially, Turkey did not allow the first request from the United States because it was violating the limit of the tonnage of the ships. Eventually the US changed that request to two small ships instead of one big vessel. But this created a big delay." said Aydin.

Russian pressure

But Turkey is also facing pressure from Russia. Last April, a US warship using Istanbul's Bosphorus waterway to participate in a NATO Ukrainian naval exercise drew swift condemnation by Russian President Vladimir Putin. Moreover, Russian pressure is predicted to grow if NATO steps up its Black Sea maritime presence.

"Russia is making pressure on Turkey not to get involved, whether as a NATO member or a good neighbor of Ukraine," claims Huseyin Bagci, head of the Turkish Foreign Policy Institute in Ankara.

"The Russians do not hide every opportunity to criticise Turkey, and not to threaten maybe but to tell Turkey that Ankara should not make any wrong step." Bagci added. 

Ankara is looking to diplomatic talks to defuse soaring tensions over Ukraine. Aware that failure could lead to a further military buildup, including more NATO ships entering the Black Sea and deeper scrutiny of Turkey's administration of the Montreux Convention.