Two years later, Mr. Assad is even less compromising. Today he claims the chance of a truce in Aleppo is “practically nonexistent.” His confidence is buoyed by a series of rebel defeats in 2016, after which populations were forced from besieged areas to Idlib Province in northwestern Syria. Today, as one Aleppo district after another falls, the rebels know resistance is futile; Mr. Assad knows that they know. His forces will make opposition areas unlivable, isolate fighters from civilians, and force both to surrender or leave.

These cleansings reflect a pattern, but the strategy behind them is still unclear. Maybe Mr. Assad believes that if these people remain they will pose a permanent threat to nearby areas under his control. Maybe he doesn’t want to spend government money on them. Or maybe his minority-led regime just wants to push disloyal Sunnis out of its heartland in western Syria. Whatever the logic, this ominous pattern — sometimes called the “green bus” strategy after the vehicles used to transport the displaced — paints a grim picture of what the people of Aleppo can expect.

The opposition, Russia, Turkey and the United States will continue to negotiate over Aleppo’s fate while Mr. Assad shapes it. One insurgent group told me that rebels were demanding humanitarian aid, an end to bombing, and a guarantee that civilians would be allowed to remain in eastern Aleppo under rebel protection. They will get none of these. Fighters will surrender or be forced to leave. Civilians can follow them into exile or place themselves at the government’s mercy. They might join their fellow displaced in Idlib, or head to the countryside east of Aleppo that is now controlled by rebel groups allied with Turkey. People close to the rebels tell me Mr. Assad’s government and Iran prefer to send the fighters to Idlib where they can fight them unrestrained, while the rebels prefer the Turkish-protected safe haven, in part because Turkey’s presence might deter violence by the regime.

Military-age men from rebel-held Aleppo face the direst future. They might be conscripted or executed, or join the tens of thousands starving in Syria’s prisons. Already, hundreds of fighters who surrendered have disappeared, according to a United Nations spokesman. The civilians who stick around are hardly safe; the Syrian government does not distinguish between fighters and those who give them aid, medical care, shelter or news coverage. Mr. Assad, his government and its soldiers and supporters see these people as traitors and terrorists. People close to the government say Mr. Assad’s troops and supporters object to the green buses: They would rather the “traitors” in Aleppo be brought to justice than be sent to Idlib.