"Sometimes," President Donald Trump told rowdy rallygoers in Dallas last week, "You have to let them fight like two kids in a lot, you gotta let them fight, and then you pull them apart."

The "them" were Turks and Syrian Kurds, who had fought, and died, alongside U.S. forces fighting ISIS.

That is before the U.S. abandoned them in a hasty retreat that was met with rocks, rotten fruit and curses from Kurds deserted by their erstwhile American allies. (Except for the oil fields; troops will be redeployed to protect those.)

The "kids" may have indeed been separated in a pause that even Trump conceded might not last in such a treacherous region.

But the real kids often aren't the combatants. They're among the casualties of the ever-spiraling crisis in Syria — this month's Global Minnesota "Great Decisions" dialogue — which is a humanitarian tragedy in which the Turkish incursion is just the latest sad chapter.

"I give these daily briefings and this week we talked about 175,000 displaced people in northeast Syria, including 80,000 children," Stéphane Dujarric, a spokesman for United Nations Secretary-General Antonio Guterres said on Wednesday in a visit coordinated by Global Minnesota. "You know," he continued, "I spew out numbers, but every one of those numbers is a human being."

A human being like Sama.

Sama's the baby, and then the toddler, featured in a searing Syrian documentary, "For Sama," screening at the Walker Art Center this Friday and Saturday and shown on PBS' Frontline on Nov. 19.

Unflinchingly filmed by Sama's mother, Waad al-Kateab, "For Sama" chronicles the siege of Aleppo by forces loyal to the homicidal Assad regime. Among these are Russians, whose warplanes bomb Aleppo into oblivion, including the hospital where Waad's heroic husband, Hamza, tirelessly tries to save lives.

For some viewers the verité of this cinema will be simply too much. The insanity is not sanitized; the bodies and blood are real, as are the emotions, especially when mothers cradle dead children such as Mohammed Ameen, murdered by a Syrian barrel bomb dropped indiscriminately on civilians who dared defy the dictatorship.

That dictator, Syrian President Bashar Assad, followed his father's merciless, murderous ways when Syria's version of the Arab Spring turned into a winter of war that seems to have no end. Assad could have, and should have, been stopped from killing his countrymen, women and, yes, children, but world powers failed them.

"When the Security Council fails to find unity on an issue like Syria, the headline is, 'The U.N. Fails in Syria,'" said Dujarric. "I feel the responsibility to explain, well, it's much more complicated than that. The sovereign member states that make up the Security Council failed to find unity on Syria. And in the meantime, the secretary general and the people that report to him in the field in Syria are distributing water, making sure people have electricity, food, medicine." As for the failure of major powers, Dujarric diplomatically said that "It is secret to no one that there are tensions between the permanent five members of the Security Council."

These tensions have many tentacles. But Assad would have lost power if Russia hadn't immorally protected Assad as it projected itself back into being a Mideast power broker.

Russian President Vladimir Putin solidified, if not cemented, his country's comeback this week as he agreed with another autocrat, Turkish President Recep Tayyip Erdogan, to jointly patrol the conquered Kurdish territory in northeast Syria that was controlled by fighters "who fought and died the hardest to bring about ISIS's defeat," said Thomas S. Warrick, a nonresident senior fellow with the Atlantic Council's Middle East Program.

"Syrian Kurdish forces quite reasonably felt that they had been betrayed by President Donald Trump's decision, and they reached out to the Assad regime and others who were aligned with the Russians to try to say, 'If the Americans aren't going to protect us, we certainly don't want to put ourselves at the mercy of Turkish forces fearing ethnic cleansing and genocide.' So they tried to ally themselves with the Assad regime, which has been carrying out a brutal civil war against the Syrian civilian population in which they used chemical attacks," Warrick added.

This brutality has been documented by many, including human rights groups, and by journalists like al-Kateab for the world to see — and to stop. But instead, Assad's crimes have been met with geopolitical paralysis.

Meanwhile, an unrepentant Russian president "got three things at the top of his priority list," said Warrick. "One is the withdrawal of U.S. forces from northeastern Syria. Two is he does so in a way that gives the United States a reputation that he will begin to publicize to say that the United States is an unreliable partner for the countries of Eastern Europe, southern Asia, the Middle East, so we can anticipate a Russian propaganda offensive to capitalize on this." And three, continued Warrick, "To take advantage of this opening to try to re-establish Russian influence in as much of the Middle East as it can."

Moscow may indeed propagandize Trump's impulsive pullout. But criticism in Washington has been withering, too, including from congressional allies like Senate Majority Leader Mitch McConnell, who wrote in a Washington Post commentary that "Withdrawing U.S. forces from Syria is a grave strategic mistake. It will leave the American people and homeland less safe, embolden our enemies, and weaken important alliances." Or, as the internationally influential Economist magazine headlined in this week's cover story, "Who can trust Trump's America?"

Other world leaders, including the president's predecessor, also failed Syrians like the brave compatriots at Aleppo's shelled hospital, who occasionally find life amid the death of their city, making their days (and the documentary) bearable.

As "For Sama" vividly depicts, Aleppo's siege was as real as it gets. But the siege is metaphorical, too, of an era when world leaders failed to stop the brutality that should shock the global conscience.

"Will you ever forgive me?" Al-Kateab plaintively asks in the film.

She's speaking to Sama. But she just as well as could be speaking to us when she adds, "We didn't think the world would let this happen."

John Rash is a Star Tribune editorial writer and columnist. The Rash Report can be heard at 8:10 a.m. Fridays on WCCO Radio, 830-AM. On Twitter: @rashreport.

Once a month, the theme of this column is determined by the "Great Decisions" dialogue on foreign policy, conducted in partnership with the nonprofit citizen engagement organization Global Minnesota. Want to join the conversation? Go to globalminnesota.org.