Syrian dictator Bashar al-Assad must be pleased at how, within a week, the conversation has shifted from his regime’s alleged use of chemical weapons to an international peace conference on Syria’s civil war.

The idea of ending the bloodshed ― and presumably addressing Syria’s chemical weapons as well ― through an accord similar to that of post-Arab Spring Yemen is certainly worth exploring. Let’s hope Assad’s foreign patron, Russia, has altered its stance enough to make some sort of deal feasible. 

The conference, however, cannot become an excuse to sweep the chemical weapons issue under the rug, not to mention the deaths of more than 80,000 in the civil war. If negotiations don’t bear fruit, and we get conclusive proof that the regime has used chemical arms, the U.S. will need to take stronger action.

Critics, naturally, will warn that increased U.S. pressure against Assad may have terrible repercussions. They will point to the Syrian reaction to recent Israeli air strikes near Damascus as “an act of war,” and to Hezbollah’s declaration that Syria will give it “game-changing weapons,” and argue that more U.S. action will foment even greater instability across the Middle East.

So here’s a suggestion that may sound counterintuitive: A more aggressive U.S. response to proof of Assad’s chemical-weapons use may be more likely to defuse the prospects of a regional conflict, in part by swaying Iran to rethink its nuclear ambitions.

Consider the scenarios. If President Barack Obama decides to act, the likely step would be to directly arm the Syrian opposition. Many of the fears that initially kept the White House from doing so ― the radicalization of the rebels, rising sectarianism, the empowerment of al-Qaida-affiliated groups ― have already come to pass, without any of the benefits or U.S. influence that would have resulted from aiding those who oppose Assad.

Yet, at the same time, there may be an even stronger argument for the U.S. to respond with limited military force of its own. If the facts conclusively point to chemical-weapons use by the regime, Obama should opt for targeted air strikes on Syria’s planes, air bases and missile-defense systems. Although a narrowly focused air campaign wouldn’t tip the balance of war in favor of the rebels, it would help make the conflict more even, given the air superiority of the regime. It would force Assad to think twice about any further use of chemical weapons, and impair his ability to do so.

Contrary to the claims of those urging restraint, such strikes wouldn’t signal the start of a sustained war effort. Operation Desert Fox, launched in December 1998 on President Bill Clinton’s watch, was a four-day bombing campaign to degrade Iraq’s ability to produce, store and deliver weapons of mass destruction. It didn’t mark a restart of the first Gulf War or even lead to broader hostilities. And, unlike Desert Fox ― which France, Russia and China all protested ― a campaign against a Syrian government proven to have used chemical weapons would probably gain broader international support. (Before such action, the U.S. would call, in conjunction with its allies, for Syria’s disarmament, which Assad would, almost certainly, rebuff.)

There will be those who will warn that direct U.S. action risks widening the war and costing hundreds of thousands of lives. If this were simply about Syria’s civil war, they might be right. But any decisions should be made in the context of the entire region.

Syria’s war has already sparked violence outside its borders, in Lebanon and Turkey. More than 500,000 Syrian refugees have flooded into Jordan, a country of 6 million. Iraqi politics, partly because of the instability next door, have deteriorated to the point where sectarian violence is rising and the fragmentation of the country is conceivable.

Then there is the real panic-inducing scenario for the region: the use of military force against Iranian nuclear sites by the U.S., Israel or both. This is not inconceivable. Negotiations between Iran and the five permanent members of the United Nations Security Council, as well as Germany, have ground almost to a standstill, largely due to Iranian intransigence. Iran continues to enrich uranium in a steady march toward the point at which observers, notably Israel, will conclude it has “breakout ability” to rush to a bomb.

Despite the preference of the Obama administration to deal with every crisis in the Middle East independently, policy makers should look at responding to Syria’s alleged chemical-weapons use in a way that positively affects the entire region. If they did, they might conclude that limited, targeted air strikes against Syria could contribute to a breakthrough on the Iranian nuclear front.

I don’t make this claim on the familiar grounds that a failure by the U.S. to act after the president’s “red line” in Syria had been crossed would embolden Iran to speed ahead on its nuclear program. That argument is overstated for two reasons. First, Iran has watched American foreign policy long enough to know that there is little consistency from theater to theater; the “responsibility to protect” doctrine was touted as motivating the Libyan intervention in 2011, yet it clearly has carried little weight in the context of Syria. Second, Iran has already violated numerous red lines set out by the international community, with little or no consequence. Iran’s leaders likely suspect the phrase has little meaning.

A more compelling argument is that the use of military force ― even of limited scope ― would cause Iran to rethink one of its fundamental assumptions: That the U.S., chastened by its Iraq intervention, won’t use military force in the Middle East for any reason.

From the Iranian perspective, this isn’t a crazy conclusion to have drawn. Obama has repeatedly spoken of how the time of war has ended, of the need to nation-build at home, of how the withdrawal of U.S. forces from Iraq was one of his legacy achievements, and of the imperative to rebalance American attention and resources toward Asia. The budget sequestration, a slow-growing economy, and fatigue of the American people after a decade of wars reinforce this conclusion, while the heavy reliance on the use of drones underscores U.S. reluctance to risk American lives overseas.

Air strikes against Syrian targets, in challenging this Iranian assumption, could help address the fundamental flaw in the current effort to curb Iran’s nuclear ambitions through diplomacy. In the current context, the threat of U.S. military force isn’t credible, no matter how many times Obama declares that Iran won’t be permitted to acquire a nuclear weapon. An Iran unconcerned about U.S. military action has little incentive to come to a diplomatic compromise, given its willingness and ability to withstand the economic pain of sanctions.

In forcing the Iranians to re-evaluate the assumption that American threats of force are hollow, limited air strikes on Syria in response to proven chemical weapons use could lead to a more engaged and compliant Iran at the negotiating table. Ultimately, the use of a little force in Syria now could save the U.S. and its allies from having to use force on a much grander scale in Iran down the road. 

By Meghan L. O’Sullivan

Meghan L. O’Sullivan, a professor at Harvard University’s Kennedy School of Government and former deputy national security adviser in the George W. Bush administration, is a Bloomberg View contributor. The opinions expressed are her own. ― Ed.