Cryptocurrency was once dismissed as a fringe experiment. Today, it sits at the center of some of the most consequential debates in international monetary policy. Governments across the developing world are no longer asking whether crypto matters. Instead, they are grappling with a more pressing question: how much control can they realistically exert over an increasingly borderless financial system?

The challenge is not merely technical. It is fundamentally geopolitical. When residents of an emerging economy can convert their savings into dollar-linked stablecoins within seconds and move funds offshore with minimal friction, the monetary tools central banks rely upon begin to lose their effectiveness. That…