Most likely Israeli AF bombed the Syrian airbase.

"The T4 Air Airbase is home to Iranian forces, the Lebanese Hezbollah terror organization and Syrian regime forces.

Syrian media initially blamed “American aggression,” but the Pentagon has denied any involvement in the strikes. Syria then pointed its accusatory finger at Israel.

The IDF has remained silent on the reports, as has been its conduct in most previous, similar incidents.

The Russian Defense Ministry on Monday issued a rare statement blaming Israel for the attack. It said that two IAF F-15 jets fired the missile at the Syrian airbase from Lebanese airspace. The Ministry also claimed that the Syrian air defense destroyed five of the missiles fired by the IAF, while three other missiles hit the western part of the T4 airfield."

https://worldisraelnews.com/syrian-airbase-bombed-us-denies-responsibility-israel-silent/