The battle for the Syrian Kurd town of Kobani has emerged as an opportunity to deal the Islamic State a military and political defeat. Maximizing the opportunity, however, requires what has been most grievously missing from the struggle against the terrorists and their so-called caliphate: persuasive, coherent and steadfast American leadership.

On Sept. 16, IS fighters attacked Kobani. Capturing the town would have given them direct control of a major Syria-Turkey border crossing. It would also weaken Syrian Kurd resistance by denying Kurd militias a major supply and recruitment center.