General Mazloum Kobani Abdi became America’s closest ally in Syria in 2014, after a stunning blitz by ISIS sucked up a territory the size of Indiana from Syria and Iraq for its pseudo-caliphate. Mazloum was courted, on the same day, by the leader of the élite unit of Iran’s Revolutionary Guards and a senior U.S. military officer. Both countries wanted an ally to confront the Sunni jihadi movement threatening their disparate agendas in the Middle East. Mazloum led the People’s Protection Units, or Y.P.G.—a militia then made up of scrappy Kurdish fighters and armed with vintage weapons—that was holding its own against ISIS. The Iranians offered more. Mazloum opted for the United States.

I first met Mazloum—a nom de guerre for Ferhat Abdi Şahin—in March, as he waged the final campaign to rid Syria of the Islamic State caliphate. He is a soft-spoken man; at the time, he carried only a handgun under his fatigue shirt. He was then sharing a forward base with U.S. Special Forces soldiers and French and British troops in the U.S.-led coalition. Mazloum’s men protected the Americans operating at bases in the northeast third of Syria. The U.S. provided air power, intelligence, and strategic advice. Mazloum led the ground war; by then, he had already lost eleven thousand troops, male and female. Under U.S. urging, Mazloum expanded the Y.P.G., in 2015, to bring in Arabs and take the fight against ISIS beyond Kurdish border areas into the Syrian heartland. The broader militia was renamed the Syrian Democratic Forces. Together, the S.D.F. and the U.S.-led coalition seized twenty thousand square miles from ISIS. The mission is not yet complete. Thousands of ISIS members still operate in sleeper cells; their leader, Abu Bakr al-Baghdadi, is also still free.

Mazloum, however, is also on Turkey’s most-wanted list. A civil engineer trained at the University of Aleppo, he became a Kurdish activist, in 1990. The Kurds have a tortured history. The world’s largest ethnic minority without a state, they were promised a country after the First World War, in the Treaty of Sévres, as the region was split up into new countries. Three years later, under pressure from Kemal Ataturk, the founder of modern Turkey, the promise was abandoned in the Treaty of Lausanne. The Kurds were divvied up into four countries—Turkey, Syria, Iraq, and Iran. With a population of thirty million, they now represent a powerful minority in each country; their political movements have variously pressed for equal rights, autonomy, or independence. In the nineteen-seventies, as Turkey tried to quash Kurdish identity, language, culture, and civil society, Kurds mobilized in the militant Kurdistan Workers’ Party, or P.K.K. It launched an insurgency in Turkey that drew Kurds from the three other countries. Mazloum was among them. The P.K.K. leader, Abdullah Öcalan, became his personal friend during the two decades that Öcalan lived in exile in Syria, before he was imprisoned in Turkey, in 1999. A rare photograph shows Mazloum and Öcalan swimming together in the Euphrates River. “For a period of time, I served in P.K.K. ranks,” Mazloum told me. “Öcalan was working here, and the people here had loyalty to him. But the Y.P.G. is not a terrorist organization.” The Syrian government also didn’t like the Kurds. Mazloum has been imprisoned five times by the Syrian government, he told me.

As the S.D.F. absorbed the old ISIS caliphate, President Recep Tayyip Erdoğan demanded a buffer zone to protect Turkey from the Kurds, even though they have not attacked across the border in years. He invaded Syria on October 9th. Picking up Erdoğan’s talking points, Trump claimed, on Wednesday, October 16th, that the P.K.K. was “probably worse at terror and more of a terrorist threat than ISIS.” The Kurds are “not angels.” The invasion “has nothing to do with us . . . The Kurds know how to fight.”

Mazloum sees it another way, “You have given up on us,” Mazloum bluntly told William Roebuck, an American diplomat in Syria. “You are leaving us to be slaughtered.” I talked to Mazloum on a scratchy telephone line on Saturday, about the five-day ceasefire brokered by Vice-President Pence last week with Turkey. The ceasefire expires on October 22nd, the day that Erdoğan meets President Vladimir Putin in Russia. The interview has been edited for length and clarity.

Is the ceasefire with Turkey holding? Is this the end of the conflict?

So far, there is no ceasefire. The Turks are still attacking on the ground and by air strikes. We have casualties—fifty martyred, just since the ceasefire was announced, and around a hundred injured civilians and soldiers.

Do you trust Erdoğan to ever engage in a ceasefire with the Kurds, given the decades of tension?

We don’t believe Erdoğan. But we are counting on American positions. Because Americans do not show a tough position toward Turkish military activity in the Kurdish region, the Turks continue killing the Kurdish people in Syria.

There are reports of the use of white phosphorus against the Kurds. The Organisation for the Prohibition of Chemical Weapons said last week that it is collecting information on the allegations. Pictures and videos have shown people suffering from what appear to be chemical burns on their skin. Have the Turks or their allies used white phosphorus or chemical weapons?

We have some cases like that. Our members are still working to figure out what material has been used against our civilians. It was white phosphorus or napalm.

Will the S.D.F. move thirty kilometres across the entire three hundred-mile border shared with Turkey, as Erdogan’s government demands? Or will it only pull back from the areas under attack, which is roughly a quarter of the border or about sixty miles?

We accepted this concept for the ceasefire just in the limited area between Sari Kani to Tal Abyad, but, regarding the other areas, we do not accept.

Will the S.D.F. allow Turkey to set up observation posts inside Syria? Erdoğan said on Friday that he wants a dozen observation posts to permanently monitor what he calls a “safe zone” inside Syria?

No. We don’t want to accept the Turks occupying the entire Kurdish area and moving Kurdish people from their lands. What the Turks are doing now is ethnic cleansing of the Kurdish.

The U.S. had about a thousand Special Forces soldiers in Syria until President Trump ordered them last week to begin a pullout. What are the Americans doing now in Syria? Are you still in contact with them?

The Americans withdrew from the Kobani area [on the border with Turkey]. We still have an American presence in Hasakah. They do not do anything. They are just watching the ethnic cleansing of the Kurdish people and the massacre of the Kurdish people. We are still in contact with them. And we are still committed to abide by our commitment. This is our duty. We still hope to work with them to counter ISIS.

But unfortunately, the Americans are not abiding by their commitment to defend our people against the Turkish incursion.