Russia’s Kilo-Class submarines were once the pride of its diesel-electric fleet — quiet, stealthy, and feared. But a string of recent failures, from the destruction of the Rostov-na-Donu in dry dock to repeated mechanical breakdowns, has raised serious questions about the state of the “Black Hole” fleet.In this analysis, we take a closer look at what’s really going wrong — sanctions, spare-parts shortages, and the limits of Russia’s shipyards — and what it all means for the future of the Black Sea Fleet.