SHERIN TAMO REMEMBERS watching the U.S. airstrikes hit the Syrian town of Kobane from across the border in Turkey. It was September 2014, and the Islamic State in Iraq and Syria had laid siege to the border town from three sides. Turkey had refused to let reinforcements through the border but let residents like Tamo escape. She watched from the Turkish side of the border as ISIS pressed farther and farther into the majority Kurdish area. Then came the U.S.

On September 27, the U.S.-led coalition began a massive, prolonged, and deadly bombing campaign in Syria, targeting ISIS units around Kobane and initiating a partnership with the Kurdish People’s Protection Units, known by their Kurdish initials YPG, that would go on to become arguably the most effective force against ISIS. “When we heard the U.S. airstrikes, we were very happy,” recalled Tamo, a Kurdish resident of Kobane. “We applauded with every airstrike on our city by saying, ‘Let our houses collapse over their heads, ISIS.’”

That partnership may now be nearing a tumultuous end as President Donald Trump’s sudden decision to grant an apparent green light for a Turkish invasion of northern Syria opened the door to a potential humanitarian catastrophe. In the latest of a long line of American betrayals of the Kurds, a White House press release issued late Sunday night, apparently following a phone call between Trump and Turkish President Recip Tayyip Erdogan, said, “Turkey will soon be moving forward with its long-planned operation into Northern Syria.”

The northeastern Syrian region is administered by a Kurdish-led faction, the Syrian Democratic Forces, or SDF, that did much of the heavy lifting on the ground during the U.S.-led coalition war against ISIS. Widely praised for their role in battling ISIS, the Kurdish forces may now be on their own - and facing a daunting battle against their historic foes in the Turkish government. “The United States Armed Forces will not support or be involved in the operation,” said the White House statement, “and United States forces, having defeated the ISIS territorial ‘Caliphate,’ will no longer be in the immediate area.”

The apparent about-face from the U.S. - though its exact contours are unclear, owing to typical Trump administration chaos - has left erstwhile allies among Syria’s Kurds with an intense sense of apprehension. A Turkish invasion could devastate the region, reshape its demography, and force a new geopolitical realignment among Kurds that would set back their push for autonomy to the days before the Syrian civil war. Like some Western analysts, the Kurds are worried about the long-term security consequences under de facto Turkish rule - not least how Erdogan’s government, with its own complicated relationship to extremists fighting in Syria, deals with the remnants of ISIS.

“They Are Going to Destroy Our Region”

Kurds in northern Syria said they feel abandoned by the United States and fear the potential violence unleashed from a Turkish operation. “It’s a crazy decision to allow Turkey to attack Rojava,” said Mustafa Alali, using the Kurdish term for the region.

Alali, a journalist who also hails from Kobane, pointed to the sacrifices the Kurdish-led coalition has made in combating ISIS, citing an estimated 11,000 SDF fighters killed in the war. “The U.S. knows very well if Turkey attacks, they are going to destroy our region. They know this truth,” he said. “For Turkey, if you’re a Kurd, you’re a terrorist.”

The Turkish government has long agitated for an incursion into northeast Syria, pointing to the Kurdish-dominated SDF as a threat because of its ties to the Kurdistan Workers’ Party, or PKK, a Kurdish organization outlawed in Turkey that has led a 40-year insurrection against the government.

“People feel terrible,” said Alali. “Everyone was not expecting [the U.S.] to allow the Turks to attack us, especially after what happened in Afrin with so many killed and arrested.” Afrin is a neighboring Syrian-Kurdish region invaded by Turkish forces in 2018. The aftermath of the invasion of Afrin saw alleged incidents of ethnic cleansing targeting Kurds, as well as vulnerable minorities like Yazidis and Christians.

“We’ve documented Turkish-backed factions arbitrarily arresting individuals, looting, harassing, and confiscating property with very little accountability. When these violations were raised with Turkey, they turned a blind eye,” said Sara Kayyali, a Syria researcher for Human Rights Watch, of Afrin.

Kayyali added that another Turkish incursion could worsen what is already the worst crisis of displacement in the world, where some 12 million have already been driven from their homes: “Syria is already facing a major displacement crisis as a result of the hostilities in the northwest and in Idlib. Any kind of instability is likely to increase this.”

Forced Demographic Change

Among other threats, Kurds in northeastern Syria fear a Turkish-enforced program of forced demographic change accompanying any invasion. The Turkish government has made no secret of its plans to resettle millions of Syrian Arab refugees in a “safe zone” under its control in northern Syria.

Turkey is home to more than 3.6 million Syrians and anti-refugee sentiment has been gradually building, leading to incidents of rioting and physical assaults targeting Syrians. An invasion would open the door to removing refugees from Turkish territory and sending them back across the border, therefore diluting the Kurdish population there.

“For years, there have been millions of refugees living in Turkey, and public opinion is now overwhelmingly against their presence,” said Mohammed Salih, a Kurdish journalist and doctoral student at the University of Pennsylvania’s Annenberg School for Communication. “A Turkish invasion of Syria would open the door to sending those refugees back. This would boost Erdogan’s credentials with the Turkish electorate and also deal a heavy blow to the YPG and PKK, by creating an Arab ‘buffer zone’ in northern Syria.”

ISIS Revived

In addition to the humanitarian and political threats, a major war between Turkey and the SDF in northern Syria could breathe life back into ISIS’s largely sidelined insurgency. Thousands of ISIS prisoners are still being held in SDF custody, including many dead-end ISIS adherents at the al-Hol camp in the northeast.

Kurdish-led forces are already struggling to maintain control over these prisoners, some of whom are citizens of Western countries. Should the region descend into chaos, it would create a fertile new recruiting ground for extremists, while potentially allowing ISIS members in custody to break free. Maintaining the prisons that hold some 12,000 ISIS fighters has, in the words of one Kurdish general speaking to NBC News, become a “second priority.”

While Trump has boasted about defeating ISIS - including in his most recent statement green-lighting the Turkish invasion - he may well be laying the groundwork for the group’s return.

Fears of an extremist resurgence helped galvanize a pushback to Trump’s decision from current and former U.S. officials. Such fears have also been echoed by the Kurdish-led movements that fought ISIS and may now be on the brink of war with Turkey.

“Every single civilian is worried about the fate of the region - let’s keep in mind that any destabilization of the region will increase the strength of ISIS,” said Amjed Othman, a spokesperson for the Syrian Democratic Council, the political wing of the SDF. “These fighters and their families in camps in northeastern Syria are presenting a very dangerous situation. In case the SDF is dragged into military combat with Turkey, the presence of these terrorists, or any chaos, will be a dangerous situation for us, the region, and for international peace. Again, the U.S. is actually abandoning the fight against terrorism.”

The SDF general who spoke to NBC News also suggested a geopolitical shift, whereby Kurds in Syria’s northeast could turn to the government of Bashar al-Assad to protect their autonomy from current encroachment. Asked whether the SDF would now seek to ally with the Syrian government or Russian forces, Othman said, “For us, we will work with any side that accepts our demands.”

Distrust of the U.S.

Sherin Tamo, the Kurdish woman from Kobane, said some are still hopeful that Trump’s decision to withdraw American troops will be quickly reversed, as similar announcements have been in the past. His statements have nonetheless already shaken Kurds’ confidence in the U.S. “Local people no longer trust the United States,” she said. “They believe that Trump is temperamental in his remarks. They live hours of anxiety and then he comes out with a modified or opposite statement.”

Like many other residents of northern Syria, Tamo is now faced with the agonizing prospect of potentially fleeing her home in the face of a Turkish offensive. “I am between two fires if Turkey invades our regions,” she said, “my duty towards my city is to stay, and my duty as a mother to save my children.”

That offensive may yet be averted, but the feeling of bitterness and betrayal among Syrian Kurds - celebrated not long ago for their dogged resistance against ISIS - has left its mark.

“When the U.S. intervened in the war against ISIS, it did not find a better partner other than the Kurds. Syrian Kurds proved to be good allies for the U.S. And with the territorial defeat of ISIS, I think America doesn’t need the Kurds anymore,” Tamo said. “All people know is that the great powers only defend their interests.”