Since spring 2022, Russia has been prevented from reinforcing its navy in the Black Sea by a near-antique international convention and some very contemporary Turkish politics. A ceasefire could change that.

Interestingly, Turkey isn’t just a facilitator of the emerging diplomacy, but also an influential actor in its own right. If some form of sustained de-escalation were to occur, the area in which new force build-ups could happen most rapidly may be the Black Sea, where Turkey has since 2022 barred warships from entering, citing the Montreux Convention.

Policymakers now need to prepare for the possibility that Ankara would react to a longer-term ceasefire by lifting those restrictions, allowing the Russian Navy to surge into the Black Sea — and potentially setting the stage for future escalation.