often conveniently forgotten: During this same period, Iran aggressively expanded its nuclear capabilities, which in turn provided it with added leverage over the West. Iran increased its centrifuge count from 3,000 to 19,000 and built a number of advanced centrifuges it didn’t have back in 2005. It also amassed thousands of kilograms of low enriched uranium, as well as roughly 200 kg of 20 percent enriched uranium — of which it had none prior to 2010.

If sanctions gave the United States more leverage, then it’s also true that 19,000 centrifuges gave Iran additional leverage. Indeed, some in Tehran contend that Iranian centrifuges forced the United States to the table. After all, it was the United States that for years refused to engage in negotiations with the group ofuranium (LEU) in exchange for fuel pads for its Tehran Research Reactor. Despite the fact that Obama welcomed Turkey and Brazil’s efforts and spelled out the specific conditions Iran needed to accept in a letter dated April 20, 2010 — all of which Tehran accepted — the United States reneged on its promise and rejected its own proposal.

There were numerous reasons Obama chose to reject the Tehran Declaration, as the Turkish-Brazilian deal came to be called, but perhaps the two most important ones were the unstoppable momentum of sanctions and the issue of Iranian enrichment.

After the failure of the 2009 nuclear negotiations, support for sanctions on Capitol Hill was strong and growing. The Obama administration chose not to oppose this pressure, but rather to delay until it had