On the two-year anniversary of the historic Iran nuclear deal, Washington is abuzz with renewed calls for confrontation with Tehran. President Donald Trump should roll back Iranian influence through pressure and sanctions, the argument goes. Some even suggest pressure can lead to regime change, failing to see the contradiction in warning about Iran’s rising influence while predicting Tehran’s downfall if only a few more sanctions are imposed.

This near-mythological potency of sanctions is rooted in Washington’s narrative on why the nuclear deal came to fruition in the first place: sanctions and pressure brought the Iranians to their knees, forcing them to negotiate their way out of their nuclear rabbit hole.

Indeed, sanctions were so effective that had Barack Obama not shifted to diplomacy and eased the pressure on Iran, the clerical regime would likely have fallen by now, critics of the nuclear accord claim.

But this narrative is simply false. It wasn’t sanctions that caused the negotiations to succeed and it wasn’t Iran that was close to collapsing right before the talks took off. As I reveal in Losing An Enemy – Obama, Iran and the Triumph of Diplomacy, a very different reality existed behind the scenes.

Undoubtedly, sanctions inflicted tremendous pain on Iran. In one calendar year, GDP per capita declined by nearly 8%; inflation increased by over 10%; and Iran’s crude oil export revenues fell by about 40%. The Iranian currency plummeted as sanctions effectively locked Iran out of the international financial system. But much to Obama’s chagrin, Iran was hurt, but it wouldn’t break.

Nor was Iran without options. Tehran responded to the sanctions regime by aggressively expanding its nuclear program – the opposite of what Washington was seeking. If sanctions were meant to change Iran’s nuclear cost benefit analysis, Tehran sought to change America’s calculus by responding to sanctions by adding more centrifuges.

In the end, the confrontation over Iran’s nuclear program became a race between Obama’s sanctions and Iran’s centrifuges.

In July 2012, in the midst of this race, a secret channel between the US and Iran was set up in Oman. The US agreed to the channel mainly to assess how close the Iranians were to capitulating their nuclear program. Tehran, in turn, showed up to gauge how close Washington was to succumbing to Iran’s ever increasing centrifuges.

By all accounts, the meeting was a failure. Neither side was ready to give an inch, let alone capitulate. But by January 2013, the situation had changed. The White House began to realize that Iran’s nuclear clock was outpacing the sanctions clock: Iran advanced its nuclear program faster than sanctions could cripple the Iranian economy.

“Sanctions never stopped their program,” Wendy Sherman, one of Obama’s lead negotiators, told me. “Every year that went by, they had more centrifuges, more capacity, and more capability.”

The situation was dire. In January 2012, Secretary of Defense Leon Panetta had estimated that Iran’s breakout time stood at 12 months. By January 2013, the break out had shrunk to only eight to 12 weeks.

Obama realized that if nothing changed, Iran would get a nuclear weapons option before sanctions could bring Tehran to its knees. This would leave the US with only two options: accepting Iran as a de facto nuclear power or war with Iran. “I think we were coming to the realization that unless something changed, we were headed toward ... some sort of military conflict with Iran,” a former Obama official admitted to me.

The only way to evade these two disastrous outcomes was to return to Oman and do what no other US administration had done before it: offer to accept enrichment in Iran in return for unprecedented limitations to Iran’s nuclear program.

This was a momentous step. Accepting enrichment was America’s strongest negotiating card, and while Obama always envisioned Iran keeping enrichment, he intended to concede this point at the end of the negotiations. Instead, due to the shortcomings of sanctions, he had to play the enrichment card at the outset in order to get talks going.

Every Obama official I interviewed – as well as their P5+1 colleagues – agreed on this point. Had the US not accepted enrichment, there would never have been a deal, despite the sanctions pressure. “That was the overriding message [the Iranians] were sending,” Jake Sullivan explained to me. “We are not going to talk seriously about any kind of nuclear deal that is a zero-enrichment nuclear deal. Period. Period. Period. Period. Exclamation point.”

Had Obama stuck with sanctions and pressure, he wouldn’t have gotten a better deal – or regime change, for that matter. He would have gotten war.

As the nuclear deal turns two, Trump’s failure to reject the illusion that a pressure-only policy makes America safer risks putting the US and Iran back on a path towards a war neither side can truly win.

Trita Parsi is the author of Losing an Enemy – Obama, Iran and the Triumph of Diplomacy and President of the National Iranian American Council.