Notably, the Kremlin said that Israel did not notify Russia ahead of the airstrike on the Syrian base. Russian President Vladimir Putin’s spokesman Dmitry Peskov called Israel’s actions “a cause for concern.”

Following Russia’s full-scale entry into the Syria civil war in 2015, both countries set up a mechanism to coordinate military actions in the country in order to avoid accidentally trading fire.

Israel, which has purportedly carried out more than 100 strikes inside of Syria since 2012, has mostly targeted suspected weapons’ convoys for the Lebanese terror group Hezbollah, a close ally of the regime of Syrian President Bashar Assad.

However, with Iran’s presence growing in the country in recent years, Israel has also begun to target Iranian infrastructure in the country. The T-4 base was most recently hit by Israel in February after an Iranian drone violated Israeli airspace after taking off from the base.