Yet even as an outcome rather than a precondition of negotiations a full rollback of the North Korean nuclear program to zero warheads is simply not an attainable near-term diplomatic objective. After the United States’s regime-changing military interventions in Iraq and Libya, the Kim Jong Un regime is not going to relinquish nuclear weapons viewed as essential to its survival. The Trump administration thus faces the choice of pivoting from the unobtainable objective of denuclearization to the alternative—an imperfect nuclear deal that would freeze North Korean nuclear and missile capabilities at their current level. In short, the template for preventing a North Korean nuclear breakout that could directly threaten the United States is the Iran nuclear agreement—the “worst deal ever negotiated.” That deal constrained Iran’s uranium enrichment program to ensure that a latent capability to produce bomb-grade fissile material remained latent. Tillerson, rejecting the Iran nuclear deal as a relevant precedent, has argued that the accord “represents the same failed approach of the past that brought us to the current imminent threat we face in North Korea.”

That “approach” was a twin strategy of pressure and engagement that the Obama administration pursued to bring Iran to the negotiating table and into compliance with its obligations under the Nuclear Non-Proliferation Treaty. The 2013 election of a reformist Iranian president, Hassan Rouhani, who had campaigned on a platform of resolving the nuclear issue to win the lifting of economic sanctions, inaugurated an intensive diplomatic effort culminating in the landmark JCPOA agreement of July 2015.

The Iran nuclear accord was a deal, not a grand bargain. As a deal, the agreement blocking Iran’s access to weapons-grade enriched uranium was transactional, not transformational. U.S. hardliners remain critical of the agreement because of this—that is, the JCPOA does not affect Iran’s destabilizing regional role and its human rights abuses. This persisting divide in the U.S. debate—whether transactional diplomacy that is not transformational should be advanced or rejected—explains how Iran can be simultaneously “compliant” with the JCPOA and not living up to the “spirit” of the accord. The same divide will shape the possibilities for nuclear diplomacy with North Korea.

The North Korean nuclear challenge is a slow-motion Cuban Missile Crisis—one that is playing out not over 13 days, as in October 1962, but over the next few years. North Korea, which tested its first nuclear weapon in 2006, is now on the verge of a strategic breakout—quantitatively (by ramping up its warhead numbers) and qualitatively (through mastery of warhead miniaturization and long-range ballistic missiles)—that directly threatens the U.S. homeland. Unclassified projections of North Korea’s nuclear arsenal by 2020 range as high as 100 warheads, which is, incredibly, approaching half the size of Britain’s.