Friday morning, with a humanitarian mission already underway, the United States began airstrikes on ISIS in northern Iraq. What had been the U.S. policy—to rely on local forces to contain ISIS while waiting for a new Iraqi government to reach a political solution—is finished. The new policy is still taking shape, but it may eventually lead to more involvement from the special operations troops who have been in Iraq for weeks.

President Obama said Thursday night he had authorized airstrikes to protect American personnel and the Yazidi minority group stranded by ISIS on top of Mt. Sinjar. A senior administration official later stressed to reporters that U.S. forces were not launching a “sustained campaign” against ISIS in Iraq.

But with the Kurds, America’s closest allies in the fight, recovering from heavy losses, some analysts and military veterans say that airstrikes alone may not be enough to turn the tide. A sustained—if small-scale—campaign may be the only way to achieve that.

The Peshmerga, the Kurdish military, had been acting as a bulwark against ISIS, keeping the group tied up on a northern front while it also battled against the Iraqi military in the south and west.

Then, starting on Saturday evening, came the waves of ISIS attacks on positions in northern Iraq. A senior administration official described it as “a multi-pronged attack across hundreds of kilometers in northern Iraq.” This official said ISIS “acted with tremendous military proficiency.”

The Kurds were overrun. The surviving religious minorities and other vulnerable groups who had lived under their protection fled into the mountains to escape ISIS.

And now these vulnerable groups—especially the Yazidi, trapped around Mt. Sinjar without food or water before an American airdrop—are at risk of being slaughtered.

That’s what triggered the current humanitarian crisis and the growing threat that impelled the U.S. to act. The airdrop mission consisted of a C-17 and two C-130 aircraft that were escorted by two F-18 fighters. The cargo planes dropped food and water for 8,000 people, according to a senior administration official, who added that there were no U.S. personnel on the ground on Mt. Sinjar.

Though the Kurds have begun a counteroffensive with assistance from the Iraqi Air Force, ISIS has continued its march, seizing new towns and critical infrastructure—including a major dam near Mosul. For the first time, some observers believe that the Kurdish homeland itself, where the U.S. embassy and military forces are stationed, is under threat.

President Obama said late Thursday that he would authorize air strikes to protect those personnel. “When the lives of American citizens are at risk, we will take action,” Obama said. “That’s my responsibility as commander in chief.”

The Peshmerga have long been considered the fiercest fighting force in the region.

Since ISIS began its rampage through Iraq in early June, both the U.S. and Iraqi governments have tacitly bet on the Kurds’ ability to repel ISIS advances in the north. But betting on the Peshmerga to hold the line now looks like a riskier proposition after ISIS broke through Kurdish defenses and set in motion the current crisis.

In truth, it was never that safe of a bet. Since early June, representatives of Iraq’s Kurdistan Regional Government have warned the United States that the Kurdish Peshmerga were not positioned to protect the Yazidi and Christian minorities in the Kurdish region.

“We have significant interests and assets in the region,” one senior Kurdish official told The Daily Beast in June, describing the message to the U.S government. “But also more worryingly, we have a Yazidi and Christian populations that are gravely under threat right now.”

At the time, the Kurdish Peshmerga did take up positions in the oil-rich city of Kirkuk, where they remain to this day. But in the case of Kirkuk, there was a strong Kurdish interest in repopulating the city with Kurds who were driven from it by Saddam Hussein.

The consensus among ex-CIA analysts, former military officers, and Iraq veterans who spoke with The Daily Beast is that the Peshmerga’s abilities were overrated. No one questions the Kurds’ willingness to fight, but their military prowess appears to have degraded in the years since the U.S. military stopped training them and withdrew from Iraq.

Douglas Ollivant, a former Army officer who advised Gen. David Petraeus in Iraq and served under two presidents in the National Security Council, expressed a view common among military and intelligence officers: “I think the general consensus among the American military people in country is that the Kurds just aren’t any better than any other military force in Iraq, and we shouldn’t be surprised that they’re having the same lack of success as the rest of the Iraqi army.”

A former Special Forces officer in Iraq who maintains extensive contacts among the Kurdish forces points out another factor affecting their performance. “The Kurds’ biggest weakness is the size of the border they have to protect from ISIS and the imperative they are under to yield nothing,” he said. “ISIS can give up territory, but the Kurds cannot.”

Air strikes against ISIS targets can weaken the group, buy time, and prevent it from massing on Kurdish forces, but according to military and CIA veterans, air power alone will not be decisive.

“The advisors need to be pushed out, if they haven’t been already,” said Nada Bakos, a CIA veteran who led the team analyzing the terrorist network that was ISIS’s predecessor in Iraq. The advisors she referred to are the special operations troops who have so far stayed away from the battlefield, offering intelligence and advice from headquarters in areas remote from the fighting.

A former Special Forces officer and Iraq veteran described how the troops currently on the ground, some 800 elite special operations soldiers, could impact the battle: “If SOF [special operations forces] advisors moved to the front, they would be able to help organize and plan the maneuver of Peshmerga, provide up-to-the-minute intelligence to protect line units, and give greater speed and fidelity to close air support. It would also give a tremendous morale boost to Peshmerga units under fire.”

That could be a great boon to the Peshmerga, but not without costs. Moving U.S. special operations forces onto the battlefield, even as advisors, “greatly raises the profile of American involvement and will eventually lead to highly visible American casualties,” according to the Special Forces veteran.

President Obama made his political career, in part, on his opposition to the Iraq war. Those casualties are something he is desperately trying to avoid. But the situation on the ground in Iraq may leave him no choice.

— with additional reporting by Eli Lake