The enduring importance of the Turkish Straits

Turkiye last week refused to allow the UK to move two Royal Navy Sandown-class minehunter ships through the Bosphorus for transfer to the Ukrainian navy on the basis that this would be a violation of the Montreux Convention. This 1936 treaty states that, at times of conflict, “vessels of war belonging to belligerent powers shall not … pass through the Straits.” The Montreux Convention is an international agreement governing the Bosphorus and Dardanelles straits, which in recent years have returned to the fore. Amid rising instability and geopolitical tensions in the region, the current context is markedly different to the international circumstances at the time the treaty was signed.
As officially announced, Turkiye cited the treaty to restrict the passage of the British ships. As a non-littoral state of the Black Sea, the UK had to request passage 15 days prior. However, despite this, Turkiye announced that it had informed its NATO ally that these warships would not be allowed to pass through the straits to reach the Black Sea for “as long as the war continues.”
Since the February 2022 appeal of the Ukraine government to exercise the convention to limit the transit of Russian warships, Turkiye has recognized the invasion of Ukraine as a war and thereby limited the passage of military vessels. Later in 2022, the Varyag, the flagship of the Russian Pacific Fleet, and Admiral Tributs, a large antisubmarine destroyer, were refused permission to enter the straits after a nine-month wait, in what Turkiye saw as a consistent application of Article 19 of the Montreux Convention. Last week’s refusal of passage for the British ships demonstrated once again Turkiye’s ultimate say over any warship if it deems its movement to be a security threat.
There is no doubt that the permission of warships to transit the straits can pose a risk to Turkish national security interests. In conflicts where Turkiye is not a belligerent party, permitting certain vessels to pass through can have the potential to draw it into the war. However, Turkiye’s refusal of the British vessels’ transit application is reflective of several facets of Turkish foreign policy that affect its interaction with its partners.
As a linchpin member of NATO that simultaneously courts Russia, Turkish oversight of the straits is illustrative of this diplomatic bind. In continually balancing its relations with NATO and Moscow, Turkiye has not only shown its indispensability to both, but also allowed the Ukraine conflict to strengthen its own position regionally and internationally. Having continually implemented the treaty to stop Russian vessels, its exercise of the same in light of the UK’s request provides Turkiye with an opportunity to appease the Kremlin. Much as it has over the last year by delaying Sweden’s accession to NATO, Turkiye is able to at once act contrary to Western interests, retain close bilateral relations with Russia and remain indispensable to both.

The straits are arguably more important than their military use, given their centrality to maritime trade traffic.

Zaid M. Belbagi

Turkiye’s at times rigid application of the Montreux Convention also serves its purposes in confirming a status quo that has remained unchanged since its adoption. Though held up as an effective treaty that allows for the careful governance of the straits, the convention — now in its ninth decade — reflects the status of the defeated Turkiye of the 1930s and is unreflective of the country’s growing power today.
Increasingly disillusioned with the treaty, which was initially designed to contain fascist Italy, Turkiye has floated the Istanbul Canal project. This would allow vessels to pass parallel to the existing straits, while providing Turkiye with greater revenue and, more importantly, giving it sovereign control over passage.
Though Turkiye’s pronouncement last week pertained to the passage of military vessels, the straits are arguably more important than that, given their centrality to maritime trade traffic. At least 3 percent of the global oil supply, mainly from Russia and the Caspian Sea, passes through the Bosphorus. Additionally, about 25 percent of the world’s wheat supply is shipped from Black Sea ports. Given that a staggering 50,000 vessels pass through these straits annually, they are not only important to the global economy but particularly to Turkiye, which has recently started charging vessels a transit fee of $4 per ton — five times higher than the previous rate.
Highlighting the ineffectiveness of an outdated treaty is without doubt Turkiye’s aim, but the Montreux Convention is unlikely to be reviewed given that, despite its current form, it allows for cargo movement in times of both war and peace, while also restricting the potential for military escalation. Despite their expressed interest in remaining dedicated to implementing the articles of the international treaty, Turkish decision-makers are aware that the Black Sea was once considered an “Ottoman lake” and the region’s maritime movement is very much a Turkish preserve.
To that end, although Ankara is currently seen to often side with Moscow, there are few states that have historically been more frequently at war with each other, with their interests directly competing. Though security concerns and international treaties often change over time, there are certain geographical chokeholds, such as the Bosphorus, that retain their strategic importance.

• Zaid M. Belbagi is a political commentator and an adviser to private clients between London and the GCC. X: @Moulay_Zaid