Commentary:

Amid the unfolding disaster in Syria, Mazloum Abdi offers some hope: The Kurdish and Arab fighters guarding the Islamic State (IS) prisoners remain at their posts. For now that is. Mr Abdi, the commander of the Syrian Democratic Forces, then offered a warning. “I don’t believe we can still hold the positions for much longer,” he said on Thursday in a telephone interview from his headquarters in Qamishli, Syria. “I can’t give you a timeline, but I can tell you it will not be a long time. If we think the Turkish operation will not stop, we cannot fight IS anymore.”

Mr Abdi’s army has more than 11,000 IS fighters in its custody. His forces are also responsible for securing the refugee camps operated by international aid organisations for IS’s women and children — as well as the group’s many victims. For now, a major refugee camp at al-Houl remains secure, he added in a statement.

Since Turkish operations into northern Syria began on Wednesday, Mr Abdi said, there have been two major prison riots. One occurred after the Turkish military bombed the Jerkin prison in western Qamishli. In both cases, Mr Abdi said his forces were able to quell the unrest. The Qamishli air strike was particularly dangerous because a prison holds a number of the foreign fighters who once migrated through Turkey to join IS’s so-called caliphate.

Mr Abdi confirmed a report that US special operations forces were taking custody of dozens of high-value IS prisoners. Those operations took place with the knowledge of his officers, he said, but there were still many seasoned fighters who could return to the battlefield if the Turkish operations continue.

If Trump cannot persuade Erdogan to pull back his army, then it’s likely that the Syrian Democratic Forces will seek a partnership with Assad.

If that comes to pass, it would be a tragic end to a once-hopeful partnership. Beginning in 2014, Mr Abdi — a member of the Kurdistan Worker’s Party, which is considered a terrorist organisation in Turkey — began negotiating the formation of the SDF. Over the next five years, it grew to 70,000 troops. Half of them are Kurdish fighters, while the rest are primarily Syrian Arabs.

With the aid of the US Air Force and the guidance of US Special Forces, the SDF was able to take back most of the territory of IS’s caliphate. The fact that the caliphate was smashed with such a light US footprint proves that effective counter-terrorism does not require tens of thousands of troops. There are currently less than 1,000 US forces on the ground in Syria.

“All the achievements for us that we accomplished with America’s soldiers are now at risk,” he told me.

For Mr Abdi, President Donald Trump’s decision to remove the handful of special operators from a safe zone negotiated this summer with Turkey amounts to a betrayal. Mr Abdi repositioned SDF forces per the safe-zone agreement with the expectation that the Turks would not encroach on the territory. “We abided by our agreement,” he said. “America and Turkey have not abided by theirs.”

It’s worse than that, actually. Mr Abdi has warned that militias which are now invading Syria with the Turkish military include former jihadists whom the Kurds had fought before. “They will pose a threat to us and our people,” he added. “They will pose a bigger threat to America’s army and its people and its interests in the future.”

Despite this dire assessment, he still said he thought it was possible for Mr Trump to get Turkish President Recep Tayyip Erdogan to back down. “I believe the only person capable of preventing this disaster is President Trump.”

If Mr Trump cannot persuade Mr Erdogan to pull back his army, then Mr Abdi confirmed what most of the US government already knows: He will seek out a partnership with Syrian dictator Bashar al-Assad.

“If our allies do not stop this catastrophe to our people, the situation will become worse,” he said. “I think an alliance with Assad could happen. If we get to this point, where we are hopeless.”

Mr Abdi has not yet reached that point. He noted at the end of the interview how sorry US commanders were when they told him they had to withdraw their troops. “We know the American army are our friends,” he said. “We believe they want to defend our people. But this decision was made by politicians, not by the military.