The recent attack by Ukraine of a Russian missile-carrying corvette stationed in the Caspian Sea more than 1,500km away from Kyiv has put the spotlight on this large, often overlooked body of inland salt water.

The Caspian Sea hosts major offshore oil and gas fields and critical maritime infrastructure, including ports, pipelines and terminals that connect central Asia to global markets. It is a key node in the so-called middle corridor trading route from China to Europe via central Asia that avoid increasingly uncertain routes via Russia in the north and Iran in the south.

China views it as a key corridor for energy supplies and its belt and road initiative that is an economic statecraft strategy that uses infrastructure connectivity to expand Beijing’s influence. The middle corridor links mainland China to Europe via Kazakhstan and Azerbaijan. Turkey, meanwhile, uses Caspian links, especially fossil fuel transit projects, via Azerbaijan, to increase its influence across the Turkic world, becoming a regional energy hub.

The 2018 Convention on the Legal Status of the Caspian Sea sets out how the Caspian’s oil, gas, and fishing resources are divided among the bordering nations. Crucially, the agreement also prohibits the deployment of armed forces from third-party countries within the Caspian’s waters. This establishes a regional security order that excludes western military presence.

For Russia, the Caspian Sea has a high value, both as........

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