An Israeli commando helicopter is said to have flown in soldiers and carried out some kind of operation southwest of Syria's capital Damascus.
According to Syrian military sources, the Israelis landed near a military base that was previously run by Iran, but was later destroyed by Israel. The British-based Syrian Observatory for Human Rights (SOHR) reports that the base houses weapons belonging to the Iran-backed Lebanese militia group Hezbollah.
The raid is said to have lasted for two hours, writes The Times of Israel.
Israel has not confirmed the incident, but Defense Minister Israel Katz says cryptically on X that the country's forces are operating "on all fronts, day and night, for Israel's security".
If the raid is confirmed, it would be the deepest Israeli operation on Syrian soil since the Assad regime was overthrown in December and an Islamist government came to power.
The reports of the raid come after Israel bombed targets in Syria on at least two occasions during the week. On Tuesday, several Syrian soldiers are said to have been killed in an Israeli attack outside Damascus.
Syria has condemned the attacks, as well as Israel's presence on the occupied Golan Heights, which they call "a violation of international law and a direct threat to peace and security in the region".
A large part of the Golan Heights was occupied by Israel in connection with the Six-Day War in 1967. Only the US has recognized Israel's sovereignty in the area, a decision that was made during President Donald Trump's first term in the White House.
