BEIRUT, Lebanon: Militants from the Islamic State captured a Jordanian Air Force pilot on Wednesday after his F-16 fighter jet went down during a military mission against the group in northern Syria.

The jet was the first to go down since a coalition of countries led by the United States began bombing the Islamic State in Syria and Iraq this year. It is also the first time since the campaign began that the jihadists have been reported to capture anyone from the military of a participating country, giving them a new form of leverage over their enemies.

The Jordanian military said in a statement reported by Petra, the state-run news service, that First Lt. Moaz al-Kasasbeh had been taken hostage after his plane “went down” and that the Jordanian government held the Islamic State and its supporters responsible for his safety.

Supporters of the Islamic State, known as ISIS or ISIL, reported the capture on social media, saying that fighters had shot the plane down with an antiaircraft missile. They posted photos of the jet’s debris and of the captured pilot in a white T-shirt and surrounded by masked gunmen. They also posted his military identification card.

The Syrian Observatory for Human Rights, a Britain-based group that monitors the war in Syria through contacts on the ground, also said that militants had brought down the plane with an antiaircraft missile.

But that claim was countered by the American military command. In a statement, the command said it had evidence that “clearly indicates” that the pilot had not been shot down. “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 overall commander, Gen. Lloyd J. Austin III, was quoted as saying.

American officials have lauded the contributions of their Arab allies, but also acknowledge that most of the strikes have been carried out by the United States, with its partners often playing a supporting role.

Those partners — Bahrain, Jordan, Qatar, Saudi Arabia and the United Arab Emirates — have avoided elaborating on their role in the campaign, mostly over fears of retribution by the Islamic State or to avoid domestic opposition from citizens who sympathize with the extremists.

Jordanian news outlets spoke with the captive pilot’s father, Safi al-Kasasbeh, who said Jordanian officials had informed his family that his son had been captured and that Jordan’s military was doing it all it could to ensure his return.

The pilot’s brother, Jawad al-Kasasbeh, said by phone that Jordan’s monarch, King Abdullah II, met with his father on Wednesday in a show of solidarity but that the family had no more information than what they had heard in the media.

“We don’t know what is the fate of my brother, and we ask God to bring him back home to us,” he said.

The pilot is in his mid-20s and had recently gotten married.

“He was very happy to start a new future,” he said.

It remained unclear whether the capture would affect the participation of Jordan and other Arab countries in the fight against the Islamic State, also known as ISIS or ISIL. But the group will most likely try to use it to its advantage; in the past, it has used hostages to demand ransoms and distributed grim propaganda videos of its fighters beheading Americans and Britons in what it has called revenge for their countries’ actions.

A spokeswoman for the allied air campaign in Qatar referred all questions about the aircraft to the Jordanian military, but said combat missions continued unabated.

“The incident has not changed flight ops for coalition sorties in Syria,” Capt. Malinda Singleton, the spokeswoman for the command, said in an email.

American pilots have voiced concerns in recent weeks about the threat of ISIS’s surface-to-air missiles and other ground fire — particularly after the recent downing of an Iraqi helicopter gunship. But American pilots typically fly well above 20,000 feet — outside the range of most of the missiles — to carry out their missions.

Jawad Anani, a former foreign minister, said he expected most Jordanians to continue to back the government’s participation in the anti-ISIS coalition.

“If something — God forbid — happens to Moaz, then it will rally people behind the idea that ISIS must be fought against with all means possible,” he said. “It will also strengthen Jordan’s resolve to fight ISIS.”

But Labib Kamhawi, a Jordanian political analyst and reform activist, said the capture could cause domestic opinion to shift against participation in the war, especially if the jihadists killed the pilot.

“It is natural for people to express such feelings: ‘Why should our children go and get killed and captured by the enemy? For what cause?’ ” he said.