The Middle Corridor, the Black Sea and the Straits: Türkiye's Place in Eurasian Trade Routes

Why It Matters

The Middle Corridor is a multimodal trade route linking China and Central Asia to Europe across the Caspian Sea, Azerbaijan, Georgia and Türkiye, without crossing Russian territory. Türkiye sits at the western end of it, where rail lines, Black Sea ports, the Bosphorus and the Dardanelles meet the European market. It is one of several competing Eurasian routes, and none of them is a complete substitute for the others.

This guide separates what is built and operating from what is announced, negotiated or merely forecast. It deliberately gives no cargo-volume or transit-time figures: published numbers vary with methodology, route definition and political intent, and many are projections rather than audited statistics.

Background

The route in plain terms

The Middle Corridor, also called the Trans-Caspian International Transport Route (TITR), is not a single road or railway. It is a chain of links operated by different states and companies.

Segment	Typical modes	Key nodes
China to Kazakhstan	Rail	Border crossings and dry ports in eastern Kazakhstan, such as Khorgos
Kazakhstan to Azerbaijan	Rail to Caspian port, then ferry or ro-ro vessel	Aktau and Kuryk (Kazakhstan); Baku/Alat (Azerbaijan); Turkmenbashi (Turkmenistan) for some flows
Azerbaijan to Georgia	Rail and road	Baku–Tbilisi corridor
Georgia to Türkiye	Rail (Baku–Tbilisi–Kars), road, Black Sea shipping	Kars, Poti, Batumi
Türkiye to Europe	Rail via Marmaray, road, sea	Istanbul region, Bosphorus, Marmara ports, Thrace

Because the route changes mode and rail gauge several times, its practical performance depends on coordination: timetables, customs procedures, tariff agreements and Caspian vessel capacity. Weak links in any of these tend to matter more than the quality of the best-built section.

Verified infrastructure and legal milestones

The following items are documented, signed or opened. Status is stated separately so that readers can distinguish them from proposals.

Date	Milestone	Status
1936-07-20	Montreux Convention on the Turkish Straits signed (in force since November 1936)	In force
2005–2006	Baku–Tbilisi–Ceyhan oil pipeline begins operation, deepening Azerbaijan–Georgia–Türkiye infrastructure ties	Operating
2013-09	China announces the Silk Road Economic Belt, later part of the Belt and Road Initiative	Policy framework
2013-10-29	Marmaray rail tunnel under the Bosphorus opens	Operating
2015-11-14	Türkiye and China sign an MoU aligning the Middle Corridor Initiative with the Belt and Road Initiative	Signed
2016-08-26	Yavuz Sultan Selim Bridge (road and rail) opens over the Bosphorus	Operating
2017-10-30	Baku–Tbilisi–Kars (BTK) railway inaugurated	Operating
2018	New Baku International Sea Trade Port at Alat opens	Operating
2018-08-12	Convention on the Legal Status of the Caspian Sea signed in Aktau by the five littoral states	Signed
2019-11	A first China–Europe freight service crosses the Marmaray tunnel	Operational milestone
2021-11	Turkic Council renamed Organization of Turkic States; 'Turkic World Vision 2040' adopted	Institutional
2022-02-28	Türkiye announces it will apply Montreux Article 19 to belligerent warships in the Russia–Ukraine war	Implemented
2023-09	India–Middle East–Europe Economic Corridor (IMEC) memorandum announced at the G20 in New Delhi	Memorandum; implementation uncertain
2024-05-21	Iraq, Türkiye, Qatar and the UAE sign a framework for Iraq's 'Development Road'	Signed framework
2025-08-08	Armenia and Azerbaijan initial a peace text in Washington; a transit route through southern Armenia is announced	Political announcement; construction not established

The BTK railway is about 826 km (roughly 513 miles) long and includes new sections in Georgia and Türkiye. It also includes a change of rail gauge, because Azerbaijan, Georgia and Central Asia use the 1,520 mm broad gauge while Türkiye and Europe use the 1,435 mm standard gauge. Freight therefore has to be transshipped or have its bogies changed near the Georgian–Turkish border. This is a physical bottleneck that no summit declaration removes.

The Turkish Straits under Montreux

The Bosphorus, the Sea of Marmara and the Dardanelles form the only maritime exit from the Black Sea. The 1936 Montreux Convention sets the rules:

• Commercial vessels: In peacetime, merchant ships enjoy freedom of transit by day and night, subject to the Convention's provisions on sanitary inspection and fees (Articles 2–3).
• Warships: Passage is regulated by tonnage, notice periods and the status of the state concerned, and Black Sea littoral states enjoy particular rights.
• War: Article 19 allows passage of warships of belligerents to be barred, with an exception for vessels returning to their bases. Articles 20 and 21 give Türkiye additional powers when it is itself a belligerent or considers itself threatened by imminent war.

Shipping through the Straits is managed under Türkiye's Maritime Traffic Regulations for the Turkish Straits (adopted in 1994 and revised in 1998), which apply traffic-separation and pilotage-related safety rules. For analysis of how the regime works, see Region Scope's explainer on the Montreux Convention and our own guide to how Montreux Article 19 kept warships out of the Black Sea. A common misconception, that Ankara can shut the Straits 'at will', is examined in our fact check.

Facts, plans and forecasts: a working distinction

Coverage of Eurasian corridors often blends three different things. This guide separates them.

• Verified facts: Opened infrastructure, ratified treaties and signed agreements (the table above).
• Plans and proposals: Projects with announcements but no completed financing or construction, such as the proposed Kars–Iğdır–Nakhchivan railway, Iraq's Development Road, or a transit link across southern Armenia.
• Forecasts: Scenario studies and official targets. For example, a 2023 World Bank study on the Middle Trade and Transport Corridor set out scenarios in which freight could grow substantially and journeys shorten if bottlenecks were fixed. Those are conditional scenarios, not outcomes.

Rules on sanctions, customs and cargo compliance differ by country, and shippers must check the regimes of every jurisdiction a cargo touches. Türkiye has not joined Western sanctions on Russia, while the EU, the United States and the United Kingdom apply their own regimes, and this affects how some companies assess route risk.

Key Players & Positions

Azerbaijan

Azerbaijan is the Caspian hinge of the corridor. It hosts the Baku/Alat port, the Azerbaijani section of the BTK line and the energy infrastructure that already links it to Georgia and Türkiye. Baku describes itself as a transit hub between Asia and Europe and has invested in ports and rail. It has also pursued a land link to its Nakhchivan exclave, which borders Türkiye and Iran but not mainland Azerbaijan. The 2021 Shusha Declaration on allied relations with Türkiye reinforces that political alignment.

Kazakhstan, Uzbekistan and Central Asia

Kazakhstan is the largest transit state east of the Caspian and the first link in the chain. Astana's official line is multi-vector: it supports several routes, including the Northern rail route through Russia, and treats the Trans-Caspian option as one of them. Uzbekistan and Kyrgyzstan back a China–Kyrgyzstan–Uzbekistan railway agreed in 2024, with construction launched in December 2024. This would add another Central Asian route to the Caspian region and beyond. Turkmenistan operates the Caspian port of Turkmenbashi and has a more cautious foreign-policy tradition.

Georgia

Georgia provides the Black Sea and rail outlet, with ports at Poti and Batumi and rail connections to Azerbaijan and Türkiye. The planned deep-sea port at Anaklia has had a contested history of tenders and political disputes, and its eventual role remains uncertain. Tbilisi positions itself as a neutral transit state and also trades with Russia and Europe.

The Organization of Turkic States (OTS)

The OTS, formerly the Turkic Council founded in 2009 in Nakhchivan, groups Azerbaijan, Kazakhstan, Kyrgyzstan, Türkiye and Uzbekistan as members, with observer participation from Hungary and Turkmenistan. Its summit documents regularly list transport connectivity, customs facilitation and the Middle Corridor among priorities. Critics outside the region sometimes read the OTS as a geopolitical bloc, while member states describe it as a cooperation platform. For background, see What Is the Organization of Turkic States?

China

China's Belt and Road Initiative treats the Middle Corridor as one of several routes to Europe. In practice, most China–Europe rail traffic has historically used the Northern route via Kazakhstan, Russia and Belarus, and Beijing keeps multiple options open. The 2015 MoU with Türkiye linked the two concepts, but alignment on paper has not meant that Beijing prefers the Trans-Caspian route to alternatives.

Russia

Russia's Trans-Siberian and related lines form the core of the Northern route, and Moscow promotes the International North–South Transport Corridor (INSTC) through the Caspian and Iran. Russian officials generally describe Trans-Caspian projects as legitimate but not as replacements for existing routes. The 2018 Caspian Convention gives littoral states, including Russia, a say over certain Caspian projects. Since 2022, sanctions and security risks have prompted shippers to reassess the Northern route, but the extent of the shift is disputed and data are contested.

Iran

Iran promotes itself as the natural transit state for the INSTC and for Central Asian access to the Gulf. Iranian officials have said they oppose changes to regional borders and are wary of transit arrangements that could marginalize Iran, notably across southern Armenia. Missing rail sections, such as Rasht–Astara, limit the INSTC's practical capacity.

Armenia

Armenia's 'Crossroads of Peace' concept proposes reopening regional transport links on the basis of sovereignty, jurisdiction and reciprocity. The Kars–Gyumri railway has been inactive since the Türkiye–Armenia land border closed in 1993. Türkiye and Armenia have been in normalization talks since 14 January 2022, with Special Representatives Serdar Kılıç and Ruben Rubinyan. The 2025 Washington announcement on a transit route through southern Armenia was a political commitment, and the legal and financial arrangements are still evolving.

The European Union and the United States

The EU treats Trans-Caspian connectivity as a priority within its Global Gateway strategy and has held investor and ministerial events on it, as well as engaging Central Asian states at summit level. Washington has supported regional connectivity and the Armenia–Azerbaijan peace process. Both emphasize diversification of supply chains away from sole dependence on Russia or on Red Sea routes.

Gulf states, India and Iraq

IMEC, announced in September 2023 by India, the United States, Saudi Arabia, the UAE, the EU, France, Germany and Italy, proposes rail and shipping links from India through the Gulf and Israel to Europe. Its implementation has been constrained by the regional security situation. Iraq's Development Road proposes a rail and road link of roughly 1,200 km (about 750 miles) from the Grand Faw port in southern Iraq to the Turkish border. Qatar and the UAE signed the 2024 framework alongside Iraq and Türkiye, which marks a Gulf-backed alternative that does run through Türkiye.

The competing routes at a glance

Route	Path	Main advantages cited	Main constraints cited
Northern	China–Kazakhstan–Russia–Belarus–EU	Established rail network and track record	Sanctions exposure, geopolitical and reputational risk since 2022
Middle Corridor	China–Central Asia–Caspian–Azerbaijan–Georgia–Türkiye–Europe	Avoids Russia, links several markets	Caspian capacity, gauge changes, multi-border coordination
Southern maritime	East Asia–Indian Ocean–Red Sea–Suez–Mediterranean	Large vessels, mature shipping network	Red Sea security disruption since late 2023, diversions around Africa
INSTC	India/Gulf–Iran–Caspian–Russia	Shorter paths for some cargo	Missing rail links, sanctions on Iran
IMEC	India–Gulf–Israel–Mediterranean–EU	Political backing from several major economies	Early stage, regional security risk
Development Road	Gulf/Iraq–Türkiye–Europe	Links the Gulf to Europe through Türkiye	Construction and financing yet to be proven

🇹🇷 Official Policy · Primary Sources

Türkiye's Position

Ankara presents Türkiye as the western anchor of several complementary routes rather than the owner of one corridor. The points below summarize official positions as stated by Turkish government sources; they are Ankara's assessments, not neutral findings.

• The Middle Corridor as a connectivity policy, not a bloc project. Turkish officials, including the Presidency in OTS and bilateral summit statements and the Ministry of Foreign Affairs in its transport and regional-cooperation diplomacy, describe the Middle Corridor as a platform for trade, transit and investment among sovereign states. The legal basis is a set of bilateral and multilateral agreements, including the 14 November 2015 Türkiye–China MoU on aligning the Middle Corridor Initiative with the Belt and Road Initiative, and intergovernmental agreements with Azerbaijan and Georgia underpinning the BTK railway.
• Impartial application of Montreux. According to the Turkish Foreign Ministry's published background on the regime of the Turkish Straits, Türkiye regards Montreux as a balanced instrument that protects freedom of commercial passage and the security of the Black Sea. In February 2022, Ankara notified that Article 19 applied to belligerent warships in the Russia–Ukraine war, while keeping the Straits open to commercial traffic. Ankara argues that strict implementation, rather than selective use, is what preserves the Convention's credibility. See also Türkiye's mediation in Istanbul in 2022.
• Deep partnership with Azerbaijan and Central Asia through the OTS. Presidency statements and the OTS's 'Turkic World Vision 2040' present transport corridors, customs digitalization and logistics cooperation as practical pillars of the Organization. Ankara describes the relationship with Azerbaijan as allied, citing the 2021 Shusha Declaration, and has supported a land connection to Nakhchivan.
• Normalization with Armenia and regional peace. Ankara's stated approach to Armenia is normalization without preconditions, pursued through the Special Representatives process since 14 January 2022. Turkish officials have also welcomed progress on the Armenia–Azerbaijan peace process, and they describe reopening transport links as a benefit to the whole South Caucasus. Related questions of historical memory are covered in the 2005 Joint Historical Commission proposal.
• Multiple corridors converging on Türkiye. Ankara argues that east–west and north–south links, including the Middle Corridor, Iraq's Development Road and energy routes such as the Southern Gas Corridor, are complementary and that routes bypassing Türkiye face geographic and political limits. President Erdoğan made this argument around the September 2023 G20 summit, in reaction to IMEC. The wider strategic logic is discussed in Türkiye in a Multipolar World, and the energy dimension in Doctrine Review's guide to Türkiye as an energy hub and in our piece on Eastern Mediterranean gas routes.

The Istanbul Canal question

The proposed Istanbul Canal, a planned artificial waterway parallel to the Bosphorus announced in 2011, is a project and not an operating facility. Ankara has said it would reduce traffic risk in the Bosphorus and has stated that Montreux would remain in force. Critics, including some opposition figures, jurists and environmental groups, argue that it raises questions about the legal regime and about environmental and financial risk. Readers should treat claims that the Canal would 'replace' Montreux as speculative, since no canal has been built and the Convention's text applies to the existing Straits.

Source Comparison

Different sources frame the same infrastructure in different ways. The table summarizes recurring framings and what the primary documents actually establish.

Question	Common international framing	Turkish official framing	What primary documents show
Is the Middle Corridor a replacement for the Northern route?	Often presented as the main alternative to Russia since 2022	A complementary, additional route that diversifies options	Both routes operate; no source establishes full substitution, and capacity differs
Role of Montreux	Sometimes described as giving Türkiye wide discretion over the Straits	A treaty with fixed rules, implemented impartially	Text of Articles 2, 19, 20 and 21 sets conditions; see our fact check and Bloc Politics
The OTS	Sometimes described as a geopolitical or ethnic bloc	A cooperation platform of sovereign states	Founding and summit documents emphasize economic, cultural and transport cooperation; see Gazetteer of Nations for Türkiye's wider diplomacy
Armenia–Azerbaijan transit route	Seen as a way to open regional trade or as a source of geopolitical rivalry	Welcomed as part of regional peace, with sovereignty respected	The 2025 Washington announcement is political; legal and construction details are not established
Volume claims	Frequently cite large percentage growth	Cite growth as evidence of momentum	Figures differ by source and often mix actuals with forecasts; this guide cites none
Istanbul Canal	Some media imply it would end or bypass Montreux	Ankara says Montreux remains in force	The canal is a project; no treaty change has been made

When reading corridor coverage, check three things: whether a number is an actual or a target, whether it covers a single route or an aggregate, and which entity published it. The same caution applies to our own reporting; our approach to sources is set out in Editorial Principles and Primary Source Standards.

What to watch

• Caspian capacity: vessel availability, port throughput and scheduling between Kazakhstan, Turkmenistan and Azerbaijan.
• Gauge and customs bottlenecks: progress on transshipment capacity near Akhalkalaki and on digital customs coordination among corridor states.
• Armenia–Azerbaijan peace implementation: whether the announced transit arrangement moves from political text to a legal and financial framework.
• Türkiye–Armenia normalization: any decision on border crossings and on the dormant Kars–Gyumri line.
• Red Sea and Black Sea security: these affect the competitiveness of southern maritime routes and of Black Sea shipping alike.
• Competing projects: funding and construction milestones for the Development Road, IMEC, and the China–Kyrgyzstan–Uzbekistan railway.

Key Terms & Related Guides

• Middle Corridor / TITR: The Trans-Caspian International Transport Route, a multimodal chain from China and Central Asia across the Caspian and the South Caucasus to Türkiye and Europe.
• BTK (Baku–Tbilisi–Kars): A railway inaugurated on 30 October 2017 linking Azerbaijan, Georgia and Türkiye, with a gauge change near the Georgian–Turkish border.
• Marmaray: An undersea rail tunnel under the Bosphorus, opened on 29 October 2013, connecting the European and Asian sides of Istanbul and used by freight and passenger trains.
• Montreux Convention: The 20 July 1936 treaty governing passage through the Bosphorus, Sea of Marmara and Dardanelles. Further explainers: Soft Power Daily and The Global Anatomy.
• OTS: The Organization of Turkic States, a cooperation platform of Azerbaijan, Kazakhstan, Kyrgyzstan, Türkiye and Uzbekistan. See our explainer.
• INSTC and IMEC: The International North–South Transport Corridor and the India–Middle East–Europe Economic Corridor, two competing or complementary frameworks discussed above.

Related guides: Multipolar Review: Türkiye and the Crossroads of a Multipolar Order, Türkiye in a Multipolar World, How Montreux Article 19 Kept Warships Out of the Black Sea, and Editorial Principles and Primary Source Standards.

---

Multipolar Review presents global and regional affairs with a dedicated perspective from Türkiye. Sections marked 'Türkiye's Position' reflect official Turkish policy and legal doctrines as stated by Turkish primary sources.

Multipolar Review Editorial Team