Questions emerged Saturday over what, if anything, Turkey gave up in exchange for 49 mostly Turkish hostages who were released by Islamic State militants in Syria after being held for more than three months.
The hostages, who were taken from a Turkish consulate in Mosul, were released after protracted negotiations between Islamic State and the Turkish intelligence agency, and Turkish officials said that no ransom was paid. That led to speculation about what other leverage the Turkish government might have used.
The release was particularly significant in light of Turkey's reluctance to join a U.S.-led coalition against Islamic State, also known as ISIS, perhaps because of concern for the fate of the hostages.
"I think it's self-evident that there was some sort of quid pro quo," said Howard Eissenstat, a Turkey expert at St. Lawrence University in New York, speaking of the release. "I think what's likely is Turkey gave some sort of guarantee that its actions against ISIS would be limited in nature and it wouldn't play a primary role in any military coalition."
The 49 hostages, 46 of whom were Turkish, included the consul, other consular officials and their families. They were captured by the Al Qaeda breakaway group on June 11, when the militants seized control of Mosul, in northern Iraq.
After their release Saturday morning, the hostages were flown to Ankara, the Turkish capital. In an interview with a Turkish broadcaster, Consul General Ozturk Yilmaz said U.S. airstrikes occasionally struck near the building where they were held and in one instance killed two Islamic State militants who were guarding it.
In a statement, President Recep Tayyip Erdogan praised "the pre-planned, carefully calculated operation secretly conducted throughout the night." He said the intelligence agency "has followed the situation very sensitively and patiently since the beginning and, as a result, conducted a successful rescue operation."
An unidentified Foreign Ministry source told the official Anadolu news agency that the intelligence agency developed a strategy — using sources in Mosul, reconnaissance drones and electronic communications — to free the hostages after analyzing previous Islamic State kidnappings in Syria and Iraq.
The same strategy was used to win the release of a group of Turkish truck drivers in early July, the agency reported.
Turkey insisted it did not pay any ransom for the release of hostages. The revenue of Islamic State, which has been called the richest terrorist organization in the world, relies in part on ransoms, and some European countries are known to have paid for the release of their citizens.
The Associated Press quoted a former Turkish diplomat as saying that the official explanation "sounds a bit too good to be true."
"There are some very legitimate and unanswered questions about how this happened," said Sinan Ulgen, who now chairs the Istanbul-based Center for Economics and Foreign Policy Studies.
It is not yet clear how the release could affect Turkey's potential involvement in the U.S.-led campaign to degrade and defeat Islamic State, which has seized large swaths of Iraq and Syria.
The Obama administration has not had success in persuading Turkey, a North Atlantic Treaty Organization ally, to join what U.S. officials say will be a coalition of more than 40 countries. "Our hands are tied because of the hostages," a Turkish official recently told Agence France-Presse news agency.
Now that the hostages are free, Turkey will almost certainly be under more pressure to take a bigger role in military action against Islamic State, Eissenstat said.
"I think it takes away an excuse," he said. He predicted that Turkey will "do enough to appease the Americans without actually stepping forward aggressively against ISIS."
If Turkey joins the coalition, U.S. fighter jets could take off from an air base in southern Turkey.
Islamic State controls large parts of northern Syria along the Turkish border; the militants have threatened to attack Turkey if it took military action against them.