As tensions boil and conflict spreads across the Middle East following U.S.-Israeli attacks on Iran, an announcement that NATO plans to set up a new force for Türkiye’s Black Sea region has fueled fresh debate on the nature of the Montreux Convention and whether it could potentially be circumvented.

Ankara has acknowledged plans to establish a naval command structure in Istanbul and a multinational corps headquarters in the southern city of Adana, where a NATO-affiliated air base is already operational.

The news comes ahead of the NATO leaders’ summit in Ankara this July as Türkiye seeks to increase its influence both within the alliance and regional security order.

Here is what is known about NATO’s proposed plan, Türkiye’s expected role and security concerns, and whether the longstanding treaty governing the Turkish Straits could be affected:

What is Montreux?

First enacted in November 1936, the 29-article Montreux Convention grants Türkiye control over the Bosporus and Dardanelles, allowing it to regulate the passage of naval warships while guaranteeing free transit for civilian vessels in peacetime.

The treaty imposes strict limits on non-Black Sea states, including caps on warship tonnage and a maximum stay of 21 days in the Black Sea.

Notably, per Article 21, Türkiye has the right to close the straits to protect itself in times of war or when it perceives an imminent threat.

What’s known about NATO plans?

According to Türkiye’s Defense Ministry, NATO is working to establish a Multinational Corps Headquarters in Adana as part of its regional defense framework, alongside a proposed naval command structure in Istanbul.

The Adana-based headquarters is expected to function similarly to NATO’s existing multinational corps in Poland and Romania, focusing on deterrence and defense coordination across a broad geography spanning the Middle East, Eastern Mediterranean, Caucasus and North Africa. The 6th Corps Command has been tasked with leading its establishment, though final approval and full multinational status remain pending.

Separately, the planned naval command in Istanbul is expected to support Black Sea security and coordination, particularly in the context of the war in Ukraine and NATO’s evolving regional posture.

Officials say these initiatives stem from NATO’s regional defense plans adopted in 2023 and are not a direct response to recent conflicts. Since 2014, and more sharply after Russia’s 2022 invasion of Ukraine, the alliance has expanded its eastern flank presence, including additional multinational battle groups and command structures.

The proposed headquarters in Türkiye would integrate into this broader system, reinforcing NATO’s ability to coordinate forces and respond rapidly to emerging threats.

Türkiye’s role, concerns

Against this backdrop, NATO’s new regional plans are bound to center its easternmost member Türkiye, which has been the alliance member most affected by the security threats spurred by the 12-day Israel-Iran war in June 2025 and the ongoing U.S.-Israel war against Iran.

The shift also reflects a broader change in NATO’s approach, moving from reacting to crises to preparing for them by positioning forces in advance so they can become immediately operational when needed.

As NATO’s second-largest army, Türkiye has taken the initiative for national and regional security planning. A multinational status for the planned headquarters will mean Ankara will be both hosting and commanding NATO land forces in the event of a crisis.

Ankara brought up security concerns about the southeastern region of the continent to NATO as far back as 2022, well before the Israeli war on Gaza and the U.S.-Israeli war against Iran. The Defense Ministry has suggested Türkiye informed NATO of its intention to establish a new multinational headquarters on its soil in 2024, during the height of the Gaza war and Israel’s aggressive expansionism.

Since the Middle East war began on Feb. 28, Türkiye was targeted by four missiles launched from Iran, all of which were intercepted by NATO air defense systems.

Within NATO’s evolving strategy, the planned headquarters is expected to serve as a key operational hub focused on threats emanating from the broader Middle East, while also anchoring Türkiye’s role in the alliance’s southeastern security architecture.

Potential impact

Questions over whether these plans could undermine the Montreux Convention have been dismissed by Turkish officials as unfounded.

From a technical legal standpoint, the treaty governs only the passage of vessels through the Turkish Straits, not land-based military infrastructure such as headquarters or bases. As such, establishing a NATO command structure in Istanbul or elsewhere in Türkiye would not, in itself, violate the convention.

Any potential implications would arise only in relation to naval activity. NATO warships entering the Black Sea remain subject to Montreux’s rules, including advance notification, tonnage limits and time restrictions. Türkiye, as the implementing authority, is obligated to enforce these provisions.

NATO operations are based on host-nation consent and adherence to international law, meaning alliance activities cannot override Türkiye’s treaty obligations.

While an expanded NATO presence could increase naval traffic through the straits, compliance with Montreux would still be assessed on a case-by-case basis for each transit, not on the existence of a base or headquarters.

Türkiye has emphasized it will maintain this balance, signaling continuity in its legal commitments alongside a more active role in NATO planning.