BEIRUT, Lebanon — Two drones crashed in the southern suburbs of Beirut early Sunday, an area that is home to many supporters of the Iran-backed militia Hezbollah, which said the aircraft came from neighboring Israel.

The crashes came a day after Israeli warplanes struck targets in Syria where, according to the Israeli military, Iran had been preparing to attack Israel using explosive-laden “killer drones.” Hezbollah, which has sent thousands of forces to Syria to fight in support of President Bashar al-Assad, said two of its fighters were killed in that strike.

The weekend events further heightened tensions between the United States and its regional allies on one side and Iran and the local forces it backs on the other. So far, the struggle has played out mostly through the diversion of oil tankers, drone attacks, covert support to militant groups and strikes on military bases said to be used by the Iranians.

But the frequency of such incidents and the heated rhetoric on both sides has raised fears that a wider conflict could be on the way.