A picture taken in the northern Israeli Kibbutz of Harduf on February 10, 2018

:: The downing of an Israeli F-16 fighter jet earlier this month by a Syrian anti-aircraft missile resulted from a “professional error” by the crew, the Israeli military said on Sunday.

Its investigation found that an anti-aircraft missile shot down the Israeli warplane while it was returning from a bombing raid on Iran-backed positions in Syria on Feb. 10. It was the most serious confrontation yet between Israel and Iranian-backed forces in Syria.

The chain of events began, Israel says, when an Iranian drone was launched from within Syria and crossed into Israeli airspace. It was shot down by an Apache helicopter, and Israel swiftly launched warplanes to target its mobile control ground station in Syria.

A senior Israel Air Force officer told reporters that of a number of aircraft that took part in the mission one plane did not deploy countermeasures and was hit. It crashed in northern Israel.

“In the operational theatre, there were a number of planes that did indeed defend themselves against the Syrian launchings while completing their mission. One of the planes that did not defend itself, was hit,” the officer said.

A summary of the investigation released by the military said that the crew had chosen “to complete the mission and not defend themselves sufficiently. Their actions did not correlate with standard procedure while under enemy fire.”

The pilot suffered serious injuries during the ejection from the U.S.-built jet and the navigator, who was also hurt, has returned to active duty, the officer said.

The crew should have defended themselves as a priority over completing the offensive mission, the officer said, adding that the intelligence to hand was sufficient for carrying out the mission successfully.

He said the “heart of the event” was “the hiatus between their completing the mission successfully and taking defensive measures and ensuring survivability.”

“The mission was completed successful and still, the plane should not have been downed, that is the standard we expect and we train for this,” he said.

The Russians, with whom Israel frequently communicates in order to avoid aerial confrontations over Syria, had no connection to the launching of the drone, the officer said.

“There was no Russian involvement in the incident,” he said. The leader of Lebanon’s Iran-backed Hezbollah group, Sayyed Hassan Nasrallah, described the jet’s downing as a very big military achievement, while Iran’s Foreign Minister Mohammad Javad Zarif said the incident had shattered Israel’s “so-called invincibility”.