President Donald Trump has pulled the United States out of the Iran nuclear deal. The bold — and misguided — decision is intended to remedy an agreement he denounced as "the worst deal ever." It is instead a blow to U.S. leadership, a rebuke to its allies and threatens to unleash a regional arms race.

Trump has been a vocal and persistent critic of the Joint Comprehensive Plan of Action (JCPOA), the multilateral agreement to cap Iran's nuclear program. The deal was reached in 2015 after years of negotiation among the five permanent members of the United Nations Security Council, Germany and the International Atomic Energy Agency. Trump dismissed it as a "horrible, one-sided deal," that was "defective at its core." He contended it allowed Iran to restart its nuclear program in 2025, postponing rather than permanently ending its nuclear ambitions, and that it did not affect Iran's other "misbehavior" in the region — its missile program or supporting organizations fighting elsewhere in the Middle East.

His criticisms are accurate. The deal delayed, rather than denied, Iran's nuclear program and ignored other elements of Iranian bad behavior. He is wrong, however, on everything else. The deal has capped Iran's nuclear programs and the postponement would allow Tehran to build trust with neighboring countries that would encourage it to give up those nuclear dreams. Significantly, the IAEA has acknowledged that Tehran has complied with the agreement. And while other Iranian misdeeds continue, the deal did not address them. The parties agreed to and accepted mutual compromise.