If there’s one thing hawks know about Iran’s leaders, it’s that they only understand force.

“When it comes to Iran,” declared Benjamin Netanyahu in October, “the greater the pressure, the greater the chance” of stopping an Iranian nuke. “As one of the architects of the sanctions regime we've had on Iran,” argued New Jersey Senator Robert Menendez this weekend, “this is exactly the process that has brought Iran to the negotiating table.” And thus, Menendez added, Congress should pass new sanctions, to go into effect in six months if Iran doesn’t agree to America’s terms in a final deal. The logic is simple: since the current sanctions have made Iran curb its nuclear program a little, more sanctions will make Iran curb its nuclear program a lot.

It’s no coincidence that the same people who think Iran responds only to force also describe Iran as a totalitarian state with a monolithic governing class and virtually no space for public expression, a kind of Persian North Korea. Netanyahu famously didn’t know that Iranians wear jeans and listen to rock music. And he has described the election of Iran’s new president, Hassan Rouhani, as essentially irrelevant because Rouhani is a mere “loyal servant” of Iran’s Supreme Leader, Ali Khamenei.

The truth is more complicated. Yes, Iran is a brutal dictatorship dominated by unelected clerics. But it’s also a country where elections matter, not because they allow ordinary Iranians to vote for whomever they please, but because they offer them a chance to tilt the balance of power within Iran’s clerical elite.

That’s what happened when Iranians elected Rouhani in June. Suffering from the economic hardship and international isolation brought on by Western sanctions, Iranians rallied behind a man they thought might ease the pain. Perhaps Rouhani’s victory surprised and dismayed Iran’s supreme leader, Ali Khamenei, who was forced to swallow it because he feared that stealing another election might provoke revolution. Perhaps Khamenei was himself frustrated by Iran’s economic isolation, and saw Rouhani as a man who could bring relief.

Either way, the sanctions did not create Rouhani’s views about a nuclear deal. They merely put him in a position to act on views he already held. Rouhani, after all, had been Iran’s nuclear negotiator in March 2005, when former President Mohammed Khatami proposed capping uranium enrichment at five percent, preventing the reprocessing of plutonium, and allowing intrusive international inspections of Iran’s nuclear facilities in return for the West’s acknowledgement of Iran’s right to enrich uranium. If those terms sound familiar, they should: They’re similar to the deal that Iran and the West struck last month. The big difference is that when the Bush administration spurned Khatami and Rouhani’s overture in 2005, Iran had 3,000 centrifuges. Today it has 19,000.

The point is that sanctions did not force a monolithic Iranian regime to cut a deal it would never have contemplated before the recent economic pain. Sanctions empowered people who had favored such a deal even before the recent economic pain. Had those people not won last June’s elections, the sanctions would not have worked. In the words of Payam Mohseni, an Iran expert who teaches government at Harvard, “The victory of another candidate, such as [hardline] former nuclear negotiator Saeed Jalili, would not have produced such a change in foreign policy despite the presence of the same sanctions regime.”

That’s why the “some sanctions good, more sanctions better” logic espoused by Menendez and Netanyahu is so wrong. Sanctions “worked” because by imposing economic pain, they helped to discredit Mahmoud Ahmadinejad and other nuclear hardliners. But if Rouhani’s comparatively soft-line approach results in even harsher sanctions, then those sanctions may begin to discredit him. As the Council on Foreign Relations’s Ray Takeyh has noted, that’s what happened during the Khatami years, when Rouhani was accused of “appeasement” for making nuclear overtures that the Bush administration spurned. Today, according to reports from Iran hardliners are poised to level the same charge. And discrediting Rouhani will be easier if they can point to tangible signs of Western bad faith.

If today’s conservatives actually studied Reagan, instead of deifying him, they might find a useful model in the way he handled the Soviet Union. Early in his presidency, Ronald Reagan brought massive pressure to bear on Moscow. But when that pressure helped bring to power Mikhail Gorbachev, a man genuinely interested in ending the Cold War, Reagan moved decisively to buttress Gorbachev at home. He did so even though it required American concessions in the 1987 Intermediate-Range Nuclear Forces Treaty that outraged Reagan’s hawkish base. And Reagan’s strategy of supporting Gorbachev worked. “If Reagan had stuck to his hard-line policies in 1985 and 1986,” wrote longtime Soviet ambassador to the U.S. Anatoly Dobrynin, “Gorbachev would have been accused by the rest of the Politburo of giving everything away to a fellow who does not want to negotiate. We would have been forced to tighten our belts and spend even more on defense.”

Today, America should make a similar investment in Hassan Rouhani, not because Rouhani will give America everything it wants, but because if he fails, America will get far less. Legislating new sanctions now, even if they don’t immediately take effect, could destroy Rouhani’s nuclear diplomacy. If that happens, we may have to wait years more for leaders willing to cap Iran’s nuclear program and end its cold war with the West. And by the time they come along, who knows how many centrifuges Iran will have?