A major shock inside Iran, whether triggered by leadership succession turmoil, economic crisis, popular unrest, or external escalation, would not remain an Iranian story. It would ripple across the Middle East and reach the central battlefield of Europe: Ukraine. For Washington and its allies, the point is not to cheer for collapse. It is to recognize that Iran is a key node in an informal authoritarian support network, and that sudden instability in Tehran could weaken that network in ways