At the top of the world, centuries of frozen stillness are giving way to open water — and with that opening comes both promise and peril. European leaders gathered this week to reckon with a paradox written in melting ice: the same climate forces unlocking shorter trade routes between continents are also exposing a region where Russian military ambition is hardening into infrastructure and presence. The Arctic, long a peripheral concern, has become a central question about who shapes the rules of a world being remade by heat.