Israeli warplanes struck an Air Force base in western Syria on Monday, killing at least two Syrian military officers and three other people, according to Arab and foreign media.

A Syrian source told Reuters that the Shayrat Airbase in the Homs Province had recently been used by the Iranian Air Force, meaning that Monday’s Israeli strike could have been a warning. The source said that one of the base’s many runways was hit in the attack.

Israeli analysts said the strike also targeted a convoy of trucks hauling Iranian weapons destined for Hezbollah.

Making Monday’s attack particularly delicate is the fact that the Shayrat Airbase is also used by Russian forces, and was greatly expanded by Moscow in recent years.