The United States expects Turkey to step up in the fight against the Islamic State group now that Turkey has secured the release of 49 hostages held by the militants, Secretary of State John Kerry said Monday.

The hostages — 46 Turks and three Iraqis — were returned to Turkey on Saturday after more than three months in the hands of the Islamic State group, which captured them when it overran the Iraqi city of Mosul in June.

Turkey, a U.S. ally and member of the NATO military alliance, has made commitments at various regional conferences to help in the effort against the Islamic State group but the help has been limited so far because “they first needed to deal with their hostage situation,” Kerry said in an appearance on MSNBC.

“Now the proof will be in the pudding,” Kerry said.

The U.S. is looking for major participation from nations in the region in the U.S.-led campaign to destroy the Islamic State group. President Barack Obama has pledged that no American troops will be involved in combat missions against the group, and the U.S. expects nations in the region to provide those.

It’s not clear how the release of the 49 hostages came about, and Turkish President Recep Tayyip Erdogan is refusing to release details.

What Turkey may or may not have done to secure the release has been a subject of speculation. Many observers expressed disbelief that the ruthless militant group would have relinquished such a big bargaining chip without getting something in return. Turkey has denied paying a ransom but has been vague on whether there was a prisoner swap with the terror group.

The Islamic State group is financing its activities through oil smuggling, according to U.S. intelligence officials, including in the area along the border between Iraq and Turkey. Kerry said the U.S. believes that the countries themselves are not involved in the oil smuggling, although individuals are still involved.

(AP)