The Israel Defense Forces fired warning shots at Syria on Sunday, after an errant mortar shell landed in Israeli territory. This was the first time Israel has directed weaponry at its northern neighbor since the Yom Kippur War in 1973.

The errant shell marked the fourth time in just over a week that the infighting from Syria has spilled into Israel.

Defense Minister Ehud Barak this week warned that Israel would respond should stray Syrian ordnance continue to strike the Golan Heights, highlighting international concerns that the civil war in Syria could ignite a wider regional conflict.

Barak's warning came days after Israel told Syrian President Bashar Assad to rein in attacks on rebels near the Golan Heights, a strategic plateau that Damascus lost to Israel in the 1967 Six-Day War and which had been mostly quiet for decades.

"The message has certainly been relayed. To tell you confidently that no shell will fall? I cannot. If a shell falls, we will respond," Barak told Israel's Army Radio, without elaborating.