President Trump's worldview and foreign policy are driven by a zero-sum game mentality, where winners and losers are determined by who gains the most or loses the most. This is a departure from the postwar international order, which is based on the idea of a positive-sum game, where all participants benefit. Trump's approach is already upending norms, alliances, and economies, and threatening longstanding relationships. His hostility towards international trade, international law, NATO, and liberal democracies is reshaping the global landscape and undermining the systems that have brought prosperity and peace for decades.