Israel reportedly struck several targets inside Syria earlier this month including a T4 airbase in Homs province where Iranians had placed anti-aircraft missiles as well as unmanned aerial vehicles.
Israel has launched attacks on sites in Syria in the past, most notably in February when it struck twelve targets including three aerial defense batteries, as well as four targets which the Israel Defense Forces described as Iranian. That attack came after the shooting down of an Israeli F-16 fighter jet by Syrian forces, and the infiltration of Israeli airspace by what the IDF said was an Iranian drone.
US intelligence assessed the Israeli aircraft may have been shot down by a barrage of anti-aircraft missiles. There are concerns that if the fresh shipments are indeed weapons, they could include more anti-aircraft missiles.
A senior Iranian security official said Iran would punish Israel for the recent airstrikes on the T4 airbase in Homs, according to Iran's semi-official FARS news agency. Ali Shamkhani, the Secretary of Iran's Supreme National Security Council, and former defense minister, said Israel has not yet realized that the era of "hit-and-run" has come to an end and it should pay the price for such "stupidity."