The domestic foundation of American global power is crumbling. Trump is less the cause than a symptom and an accelerant. Since the Cold War ended, the United States has pursued global primacy under an implicit bargain with the public: dominance would come cheap. Today Americans are no more willing to bear serious costs for foreign policy than they were in the 1990s. But a far more competitive world is driving up the price of upholding U.S. commitments. No matter who wins the White House in 2028, this gap will constrain American power around the world. In a new @CarnegieEndow paper, I trace the U.S. foreign-policy consensus from the Cold War to the present and outline three scenarios for the future:

The Iran war is a crisis of American governance. Nobody voted for it. Trump ripped up the nuclear deal for partisan reasons and then launched an attack he thought would be quick but that every decent analyst said would unfold basically as it has. Even so, Congress won't end it.

Trump's Iran paradox: he wants to squeeze Iran without returning to all-out war, but the more effectively he squeezes Iran, the more incentive Iran has to escalate and force him to back to all-out war.

U.S. foreign policy is beset by virtue-signaling moralism claiming to save the world and vice-signaling immoralism seeking to dominate the world — often amounting to the same thing.

Three longstanding axioms of U.S. policy have led America to war and defeat in Iran: 1. Iran is a malign, aggressive country solely because of the nature of its regime, regardless of how the United States and regional allies treat Iran; 2. Iran's activities pose a near-existential threat to the United States; 3. Diplomacy is weakness and sanctions don't work, leaving military force as the only way to reduce the threat.