Direct proof of use
The F-35 Lightning II appears in the 2011 Syrian Civil War record through Israeli F-35I Adir operations disclosed in May 2018. NPR, republished by CapRadio, reported that Israeli Air Force commander Maj. Gen. Amikam Norkin said recent airstrikes against Iranian targets in Syria were carried out by the F-35, making it the newly fielded aircraft's first operational attack.
The same account cited Haaretz reporting that Norkin showed an F-35 over Beirut and said the fighter did not participate in the latest Syria strike but had participated in two previous ones. The direct evidence therefore supports Israeli operational F-35 strike use in the Syria-Iran theater, while leaving the precise dates and target sets of the two F-35 strikes incompletely public.
Sources: NPR F-35s Over Syria, Defense Post F-35 Airstrikes
Timeline
On May 10, 2018, the Syria-Israel-Iran escalation included Iranian rocket fire toward Israeli positions and large Israeli strikes on Iranian targets in Syria. In later remarks, Norkin described the Iranian rocket fire, more than 100 Syrian surface-to-air missiles fired at Israeli aircraft, and Israeli attacks on Iranian targets and air-defense batteries.
On May 22, 2018, Israeli and defense press reporting carried Norkin's public disclosure that Israel had used the F-35 operationally. Defense News reported the IDF announcement that Israeli F-35I Adir aircraft were already flying operational missions and that Israel was the first country to use the F-35 in operational activity. Defense News also corrected its story to note that although Norkin spoke about recent Syria airstrikes, he did not specify where the F-35 strikes took place.
Sources: NPR F-35s Over Syria, Defense News Combat Debut, Defense Post F-35 Airstrikes
Narrative
The documented user was Israel, and the variant was the F-35I Adir, Israel's national F-35 configuration. Public accounts framed the disclosure around Israel's campaign against Iranian military infrastructure and related air-defense threats in Syria, not as a Syrian government or opposition possession case.
The best-supported role is long-range or deep strike by a stealth combat aircraft. The sources do not identify the exact weapons released by the F-35I aircraft, the specific targets of the two F-35 strikes, sortie routes, battle-damage assessment, or whether every relevant strike occurred inside Syrian airspace. Those details are not treated as established in this record.
Sources: NPR F-35s Over Syria, Defense News Combat Debut, Defense Post F-35 Airstrikes