The framework nuclear deal with Iran could be a regional and global geopolitical game changer and constitute the defining foreign policy legacy of President Barack Obama's presidency.

Suspicions that Iran is using its peaceful nuclear program as a cover for clandestine weapons acquisition have persisted for a long time. Nuclear weaponization by Iran would have a series of negative consequences for every component of the nuclear arms control agenda, from increasing proliferation pressures in and beyond the region to heightened risks of nuclear terrorism, use of nuclear weapons, and setbacks to efforts to cut global nuclear stockpiles and reduce their role and salience in national security doctrines.

No credible evidence exists that Iran ever crossed the threshold into weapons production. But it continued to work on its domestic enrichment and nuclear energy program that moved it technologically ever closer to a weapon. The aim of stopping Iran from developing a nuclear capability became a lost cause over the course of this century. The real policy challenge was how to prevent it from overt weaponization: that is, to accept it as nuclear-capable but not accept it as, nor provoke it into becoming, nuclear-armed.