A Jordanian F-16 jet crashed Wednesday in an area of northeastern Syria under the control of Islamic State militants, who quickly captured the pilot, according to statements from both sides.
Jordan is part of a U.S.-led coalition that has been conducting airstrikes against Islamic State since September, after the militants seized control of large areas of Syria and Iraq during a summer offensive.
Islamic State claimed it had shot down the plane with an antiaircraft missile. Jordan confirmed that and U.S. military officials initially agreed, saying it was the first time Islamic State had downed a plane involved in the aerial campaign, dubbed Operation Inherent Resolve.
But the U.S. later issued a statement insisting that Islamic State had not shot down the F-16, although it did acknowledge that the pilot was captured.
"Evidence clearly indicates that ISIL did not down the aircraft as the terrorist organization is claiming," U.S. Central Command said, referring to Islamic State by an acronym.
U.S. Army Gen. Lloyd J. Austin III, who is overseeing all coalition military operations in Iraq and Syria, called Jordanian forces "highly respected and valued partners."
"We strongly condemn the actions of ISIL, which has taken captive the downed pilot," Austin said. "We will support efforts to ensure his safe recovery, and will not tolerate ISIL's attempts to misrepresent or exploit this unfortunate aircraft crash for their own purposes."
The Jordanian state news service Petra said the incident occurred while "several airplanes of the Royal Jordanian Air Force were conducting a military operation on the lairs of the terrorist Daesh organization in the Syrian area of Raqqah." Daesh is an Arabic acronym for Islamic State.
Jordan's government spokesman, Mohammad Momani, told satellite TV station Al Hadath that the pilot "was shot at from the ground by rocket missiles and was brought down." He said that a rescue attempt before the pilot was captured had failed, and that the government was following "all necessary procedures to ensure the pilot's safety."
State television later broadcast interviews with prominent Jordanian Islamic leaders calling for the pilot's release and discussing Islam's mercy.
Militants in Raqqah posted photographs online purportedly showing fighters holding the pilot, whom they claimed to have shot down with a heat-seeking missile. In one photo, the pilot is being escorted from a body of water by four men, his face bloody. In another, he appears surrounded by about a dozen armed and uniformed men, one bearded figure in fatigues holding him by the neck.
An Islamic State media activist tweeted a picture of the pilot's military identification card. Supporters of the group also uploaded an image of the plane's canopy displayed on a stand in Raqqah's main square, and claimed the pilot was being held in a cage "until his fate was determined."
The pilot, Lt. Moaz Kasasbeh, 26, comes from Al Karak, about 55 miles south of Amman. He attended King Hussein Air College, recently married and had posted a photo of himself on Facebook posing in front of a warplane.
On Wednesday, his relatives pleaded for his release.
Kasasbeh's brother, in an interview with local Radio Balad, appealed to Islamic State for mercy by emphasizing the pilot's piety.
"We call upon you to leave him, oh brothers. This is a military man executing orders. May Allah reward you," Jawad Kasasbeh said, "Search his clothing, you'll find his Koran with him."
Other relatives told local media they were seeking a prisoner exchange: the pilot for Sajida Rishawi, a would-be suicide bomber jailed after her explosive belt failed to detonate in Amman in 2005.
Rishawi, an Iraqi national, had previously joined an attack on western hotels in the Jordanian capital orchestrated by Abu Musab Zarqawi, the head of Al Qaeda in Iraq, which killed 38 people.
While such an exchange goes against U.S. policy, it would not be out of the question in Jordan, analysts said.
"All options are open regarding his fate," Jordanian political analyst Hassan Abu Haniyeh said in Amman.
"The Islamic State has demonstrated pragmatism when it comes to hostages. It may also take this opportunity and use Kasasbeh like Cantlie, where he will renounce the fight against the Islamic State and say 'This is not our war' and things of that nature," he said, referring to another Islamic State captive, British photojournalist John Cantlie, who appeared in an online video released by the militants this fall criticizing Western leaders.
The pilot's capture ignited a furor on social media in Jordan, a conservative, mostly Sunni Muslim. They started a Twitter campaign, "We Are All Moaz," demanding his release.
Others blamed the government in their tweets for putting "men like Moath between the rock of military orders and the hard place of Daesh."
A military analyst said the pilot's capture was more likely to cement than fracture the U.S. coalition.
"It shows that this is a real war, not simply the use of air power by the U.S. against ISIS," said Anthony Cordesman, a military analyst at the Center for Strategic and International Studies in Washington, using another acronym for the group.
While the circumstances of the pilot's capture were largely still unknown late Wednesday, Cordesman said he also didn't expect Jordan to back away from the air campaign. Iraqi forces have suffered setbacks against Islamic State this year, but also recent victories, with Kurdish peshmerga forces freeing trapped Yazidi religious minorities in northern Iraq and Iraqi soldiers securing the Beiji refinery to the south.
"I don't think you're going to find losing a single aircraft is going to intimidate the Jordanian government or the people," Cordesman said, "It is a war where the Arab coalition has a role and is actually fighting, like the advances the Kurds had with the Yazidis or the advances by the refinery. These types of advances tend to boost coalitions, not weaken them."
Special correspondent Bulos reported from Amman and Times staff writer Hennessy-Fiske from Baghdad.