Iran-backed forces in Syria said on Thursday they would respond forcefully to an Israeli strike on Wednesday evening in the second such strike within a week.
The Syrian defense ministry said in a statement that one soldier was killed in the attack that took place at 11:34 p.m. (2034 GMT) and targeted a communications tower and caused some material losses near Palmyra.
Israel has kept silent about the strikes that came days after another attack in the Homs countryside, wounded six Syrian soldiers.
Israel since 2017 has been mounting attacks on what it has described as Iranian-linked targets in Syria, where Tehran-backed forces including Lebanon's Hezbollah have put down a presence since deploying to help President Bashar al-Assad in the Syrian conflict that erupted in 2011.
A statement by the so-called operations room of Assad's Iran-backed allies said the response to the strike would be "very cruel", adding casualties would have been much higher had its forces not been well spread across the desert area.
"As a result of this attack a number of martyrs and injured from our Mujahedeen brothers have fallen," the statement said without elaborating.
"We have taken a decision to respond to this attack in revenge for the martyrs and the blood of the injured and the response will be very cruel," said the statement.
A senior military source who requested anonymity said the strikes hit among other targets the T4 air base where Iran-backed militias launched drone strikes in recent months against US bases in northern Syria.
The Palmyra area where the strikes were conducted are close to a major concentration of Russian bases and where its troops conducted in recent days maneuvers with Syrian troops, military experts say.
Israel wants Iranian and Iran-backed forces kept away from its border and more broadly, removed from Syria entirely.