A great tragedy has unfolded in the Sinjar region of northern Iraq, and it may not be over. At least 500 people from Iraq's Yazidi religious minority have been slaughtered by militants from the Islamic State in Iraq and Syria (ISIS), a group so radical even Al-Qaeda disowned it. Tens of thousands of Yazidis escaped the slaughter only by fleeing to a barren mountaintop, where they have been stranded and could soon die of thirst. While 20,000 Yazidis have managed to escape, aided by the first U.S. airstrikes in Iraq since 2011, thousands if not tens of thousands remain stranded.

It remains to be seen if the historic resumption of U.S. military operations in Iraq will be sufficient to prevent an even greater massacre of the Yazidis, or of the larger ethnic Kurdish minority of which Yazidis form a part. The frontlines between ISIS and Kurdish Pashmerga forces in Iraq are currently under 30 miles from the main Iraqi Kurdish city. But there is one thing about which we can be certain: failed U.S. policy in the region has brought us to this point, and more minorities throughout the region will be at risk unless there are fundamental reforms.

At the core of failed U.S. policy toward the region is a sort of myopia about the rise of ISIS. While the group was once known as Al-Qaeda in Iraq, it was dramatically weakened there by 2011. It regained its strength by exploiting the conflict in neighboring Syria--changing its name to Islamic State in Iraq and Syria--to attack and conquer areas under Syrian rebel control. In January, Syrian civil society activists and armed rebels alike mobilized to attack ISIS's international headquarters in Syria. But ISIS staved them off, and then regrouped to attack Iraq's second city of Mosul from Syria six months later.

America's next "Sinjar moment" in the region could very well be in Syria. Earlier today, ISIS captured a string of strategic rebel towns in northern Syria, aided in part by U.S. weapons captured from Iraqi forces in Mosul. If ISIS advances another 15 miles west, it will be able to sever all humanitarian supplies into Aleppo City, Syria's largest municipality where hundreds of thousands of people still reside. Tens of thousands more people who fled the city for its northern countryside would also be in immediate danger of slaughter.

Yet if one were to judge by recent Congressional hearings on ISIS, all woefully mislabeled as covering only the "Crisis in Iraq," one might come away with the impression that the past three years in Syria had never happened. Syria receives scant mention in these hearings, either from Congressional committee members or from witnesses in the Obama Administration. In fact, multiple Administration sources have even told me that personnel working on Iraq have successfully minimized the involvement of personnel working on Syria in their deliberations.

All this as fighters from the Islamic State in Iraq and Syria dart back and forth across the Syrian-Iraqi border to dramatic effect. When ISIS captured Mosul in Iraq, they also captured advanced U.S. weapons abandoned by Iraqi forces there. These weapons were then used to rout mainstream rebels from eastern Syria, enabling ISIS to turn north to areas of both Syria and Iraq that house large minority populations. In late July, ISIS reached the main Syrian Kurdish city, forcing Assyrian Christians in the city to flee en masse. On August 1st, as ISIS scored parallel advances on Iraqi Kurds, it was the Yazidis' turn to flee -- but they found themselves stranded on a mountaintop.

As long as the American government maintains its current myopia toward the conflict in Syria, religious minorities across the region will continue to die. ISIS will maintain its edge relative to  the Syrian rebel forces who wish to dislodge them, and Syria will continue to serve as a rear base for ISIS attacks on neighboring states. As new territories come under ISIS control, even temporarily, more religious minorities will face the fates of the Christians of Mosul and the Yazidis of Sinjar. American policy will continue to fall short of saving the region's religious minorities.

For a better outcome, there must first be an an end to America's selective humanitarianism on the killing in Syria. President Obama justified the Iraq airstrikes as helping innocents facing "violence on a horrific scale" or even "genocide," and he appears to have U.S. public support. Yet that same American public was adamantly against airstrikes when it was Syrian children being slaughtered in Assad regime chemical attacks. In that case, only a diplomatic agreement ensued, and the horrific violence continued.

At least 60,000 people have lost their lives in Syria since the U.S.-Russian chemical weapons deal of September 2013. The Assad regime has dropped over a thousand "barrel bombs" on Syria's largest city alone, with the bloodiest period coming during peace talks that the regime scuttled. Assad's jailers have continued to inflict the most grotesquely painful tortures imaginable on some 150,000 detainees in regime prisons.

Early this month, my colleagues and I facilitated a visit to Washington, D.C. by "Caesar," a regime defector who smuggled evidence from regime detention centers. Multiple U.S. officials were moved to tears by his photographs. Obama's war crimes ambassador Stephen Rapp declared Assad's detention centers unparalleled since the Nazis. But there has been no action. It seems that torture chambers on par with the Nazis are not "violence on a horrific scale" sufficient for U.S. airstrikes.

That is a shame, because anti-Assad Syrians can play a powerful role to stop the growth of ISIS. In eastern Syria today, a shadowy guerrilla movement calling itself "White Shrouds" has commenced a campaign of assassinations against ISIS leaders, declaring: “The Syrian people...rose up against injustice, not to replace [Assad's] tyrannical rule with another oppressor.” Locals in one major city have held multiple protests demanding that ISIS leave their land, while Sunni tribesmen in the countryside have even commenced an armed uprising against ISIS rule.

The United States should empower these local anti-Assad Syrians, and the thousands like them across Syria, who have been fighting a two-front war against both Assad and ISIS these past eight months. While President Obama's $500 million request from Congress for this purpose is most welcome, Friday's airstrikes showed that he need not wait for Congressional approval, and today's conquests by ISIS in northern Syria show that he must not wait any longer. 

Eastern Syrian tribes that have revolted against ISIS need advanced weapons, such as guided anti-tank missiles, to contend with superior ISIS firepower. Moderate brigades around Aleppo such as the Nur al-Din Zanki Movement, Mujahideen Army, the Hazzm Movement, and the Kurdish Front need similar weapons, and may require airstrikes within days to avert another humanitarian catastrophe. Now is the time for President Obama to authorize immediate U.S. airstrikes on heavy weapons, held by both ISIS and Assad, that are used to decimate moderate rebels and slaughter Syrian civilians.

Ghanem is the senior political adviser and government relations director for the Syrian American Council in Washington, a board member of the Coalition for a Democratic Syria, and a fellow at the Syrian Center for Political and Strategic Studies.