A mortar shell from Syria landed in the Golan Heights Monday, prompting the IDF to return fire for the second time in two days, the first time it has fired into Syria territory since the Yom Kippur War in 1973.

The exchange came just hours after an appeal for restraint from all sides by UN chief Ban Ki-moon.

An Israeli security source confirmed that troops had returned fire after a mortar round from Syria hit an Israeli position in the central sector of the strategic plateau, causing no casualties or damage.

“Israeli troops fired a warning shot towards the source of fire,” the source told AFP, speaking on condition of anonymity.

Both mortar shells on Sunday and Monday landed in the same approximate area…on open ground… in the central Golan Heights,” a military spokeswoman said.

Syrian rebels immediately turned their ire on Israel Sunday, charging that the warning shot brought out Syrian President Bashar Assad’s forces and ruined an assault by the opposition fighters which supposedly was on the verge of forcing Assad to surrender.

Analysts suspect that Assad will use Israel as his “last card” and turn his guns on the Golan Heights in a last-ditch effort to save his life if the Syrian Free Army appears to be about to vanquish him.