THREE and a half years into a war that has left 200,000 dead, forced more than 10m from their homes and sucked in America, Russia and a host of regional meddlers, the UN has a new plan for Syria: “Aleppo first”. It seeks to fix a local ceasefire in Aleppo, once a proud and bustling metropolis of 3m that has been reduced to a pockmarked carcass of mostly empty buildings, in the hope of gradually “freezing” battles elsewhere.

Don’t hold your breath. The limited scope of the initiative, proposed on November 10th by Staffan de Mistura, the UN’s special envoy, underscores the intractability of this century’s bloodiest conflict. A break in the fighting that has split Aleppo in two would certainly cheer its surviving residents, many of whom no longer care who wins. But too many factors militate against even a limited local ceasefire, let alone a negotiated peace.

President Bashar al-Assad’s government said it would study the ceasefire plan, which Mr de Mistura described as a potential building block for a wider solution. “Of course they won’t say no,” says Emile Hokayem of the International Institute for Strategic Studies, a think-tank in London. “Assad likes anything that appears to bolster his legitimacy.” Yet he notes that previous Syrian ceasefires have tended to come in two contexts: either regime forces have besieged a rebel district and offered a choice between starvation and surrender, or a halt to fighting has proven tactically useful, allowing the government to redeploy forces elsewhere.

In fact, Mr Assad has been doing better lately. The American-led air assault against Islamic State (IS) and other jihadist groups has battered some of his foes, and allowed him to pose as an ally in fighting terrorists. Mr Assad has ramped up his own, far less discriminating, aerial bombardment of rebel areas. And he has been able to release ground forces to make gains in some places, including Aleppo, after months of stalemate.