Israeli forces fired into Syria on Sunday in what the military called a warning, after stray munitions from fighting between Syrian troops and rebels hit the Israeli-occupied Golan Heights.
The incident, described by Israel Radio as the first direct engagement of the Syrian military on the Golan since the countries' 1973 war, highlighted international fears that Syria's civil war could ignite wider regional conflict.
An Israeli security source said the military fired in the direction of a Syrian army mortar crew that had launched a shell which overshot the Golan disengagement fence on Sunday, exploding near a Jewish settlement without causing casualties.
In a statement, the Israeli military said soldiers had "fired warning shots towards Syrian areas."
"The IDF has filed a complaint through the UN forces operating in the area, stating that fire emanating from Syria into Israel will not be tolerated and shall be responded to with severity," the statement said.
There was no immediate comment from the 1,000-man United Nations Disengagement Observer Force which patrols the area.
Spillover violence this month from Syria onto the Golan has jangled the nerves of Israelis worried that the once-quiet front will add to threats facing the Jewish state from Islamic militants in neighboring Lebanon, Gaza and Egypt's Sinai.
There have been similar worries in Turkey, Jordan and Lebanon about incidents on their own borders with Syria, where forces loyal to President Bashar al-Assad have been battling rebels for 19 months.
