Syrian rebels mentored by Turkey said they were positioned to launch an assault to drive the Islamic State out of the strategic town of al-Bab today, but it remains unclear whether they will actually throw themselves into what most analysts agree will be a bloody battle.

Pro-government dailies trumpeted the news of the Turkish-backed rebel advance, saying the forces were only 2 kilometers (1.2 miles) from the mainly Sunni Arab town. But the English-language Daily Sabah quoted a Free Syria Army commander as saying the operation “could take days or weeks.” The commander added, "We will see how reinforced [IS] is in the town.”

Al-Bab has emerged as something of a test of Turkish resolve in Syria, not against IS but against the Syrian Kurds. The Syrian Kurds are desperate to lay their hands on al-Bab because it would allow them to link the large, uninterrupted swath of land they rule east of the mainly Arab town of Manbij to the mainly Kurdish enclave of Afrin that lies further west. Turkey says it will not permit further expansion of a contiguous Kurdish-run zone along its borders but has faced stiff resistance from Russia, which controls the skies over al-Bab.

Until recently, most analysts concurred that Russia would prevent Turkey’s rebel proxies from taking al-Bab because of the threat they would pose to Syrian regime forces in Aleppo, just as they appear to be gaining control over the war-ravaged city. And while Turkey has backed the rebel advance from the ground, Turkish jets have not taken part in any offensive action since last month’s wave of sorties against Syrian Kurds, presumably because of Syrian threats to shoot them down.