Part of the problem is the 1936 Montreux Convention, which limits the number, transit time, and tonnage of naval ships from non-Black Sea countries that may operate in the Bosphorus. For example, non-Black Sea state warships in the strait must not displace more than 15,000 tons apiece. No more than nine non-Black Sea state warships, with a total aggregate tonnage of no more than 45,000 tons, may pass at any one time, and they are permitted to stay for no longer than 21 days. To be sure, NATO navies have shrunk since the Cold War, reducing the number available for Black Sea operations. Yet the limits remain a problem nonetheless.
I especially liked the idea of breaking the 21-day limit with the Danube River loophole.
My own ideas for working around the convention limits were modularized auxiliary cruisers that could be disarmed in port to make them no longer warships, which I suspected would reset the 21-day clock if their entry into the Black Sea as a civilian ship triggered the convention; and the use of low-flying airships.
That's for presence on the sea during peacetime to show the non-Russian flags.
Most NATO force allocated for the Black Sea should be land based and designed to hurt the Russians in wartime as an economy-of-force front.
