Turkey’s president, Recep Tayyip Erdogan, once aspired to lead the Muslim world. At this time of regional crisis, he has been anything but a leader. Turkish troops and tanks have been standing passively behind a chicken-wire border fence while a mile away in Syria, Islamic extremists are besieging the town of Kobani and its Kurdish population.

This is an indictment of Mr. Erdogan and his cynical political calculations. By keeping his forces on the sidelines and refusing to help in other ways — like allowing Kurdish fighters to pass through Turkey — he seeks not only to weaken the Kurds, but also, in a test of will with President Obama, to force the United States to help him oust President Bashar al-Assad of Syria, whom he detests.

It is also evidence of the confusion and internal tensions that affect Mr. Obama’s work-in-progress strategy to degrade and defeat the Islamic State, the Sunni Muslim extremist group also called ISIS or ISIL. Kurdish fighters in Kobani have been struggling for weeks to repel the Islamic State. To help, the Americans stepped up airstrikes that began to push the ISIS fighters back, although gun battles and explosions continued on Wednesday.

But all sides — the Americans, Mr. Erdogan and the Kurds — agree that ground forces are necessary to capitalize on the air power. No dice, says Mr. Erdogan, unless the United States provides more support to rebels trying to overthrow Mr. Assad and creates a no-fly zone to deter the Syrian Air Force as well as a buffer zone along the Turkish border to shelter thousands of Syrian refugees who have fled the fighting.