WASHINGTON, March 19 (Xinhua) -- A U.S. F-35 fighter jet was forced to make an emergency landing on Thursday at a U.S. military base in the Middle East after it was struck by what was believed to be Iranian fire, according to a CNN report citing two sources familiar with the matter.

The incident would be the first time Iran has hit a U.S. warplane since the United States and Israel launched an attack on Iran on Feb. 28, said the report.

The jet was "flying a combat mission over Iran" when it made the emergency landing, Tim Hawkins, a spokesman for U.S. Central Command, was quoted as saying.

"The aircraft landed safely, and the pilot is in stable condition," Hawkins said. "This incident is under investigation."

Both the U.S. and Israeli forces are flying F-35 jets in the conflict with Iran, said the report, noting that the aircraft costs upwards of 100 million U.S. dollars.

Earlier on Thursday, U.S. Defense Secretary Pete Hegseth said at a Pentagon press conference that Iran's air defenses have been "flattened."

U.S. Chairman of the Joint Chiefs of Staff Dan Caine said at the press conference that Iran retains "some capability" to attack assets of the United States and its allies in the Middle East, including oil facilities.

The U.S.-Israeli conflict with Iran escalated after an Israeli strike on Iran's South Pars gas field on Wednesday, with Qatar later reporting fires and extensive damage at liquefied natural gas facilities following Iranian strikes, sending oil and gas prices surging again on Thursday.  ■