JERUSALEM — The Israel Defense Forces fired a warning shot, in the form of a guided missile, at the Syrian military on Sunday after a Syrian shell exploded in the Golan Heights for the second time in recent days.

Israel has not fired at Syria since the 1973 Yom Kippur War.

"In the midst of Syrian infighting, a mortar shell fired by the Syrian army struck near an [IDF] outpost at Tel Hazeka," IDF spokesman Brig.-Gen. Yoav Mordechai told The Jerusalem Post. The shell failed to cause injuries or damages, but was one of a series of shells that landed in Israeli territory.

"In light of the policy instituted by IDF Chief of Staff, Lt.-Gen. Benny Gantz, a warning round was fired back into Syria. We don't believe it caused injuries or damages," Mordechai added.

Military sources said the IDF fired an advnaced Tapuz-type missile at a Syrian artillery cannon.

At the same time, Israel sent a warning message to the UN, saying that any further firing into Israel will result "in a real response," sources added.

Israel limited its return fire, since its policy is to only fire intensively in response to coming under major Syrian fire. "We didn't continue firing because this was one mortar we were responding to," the source said.

"We will not accept any firing into our territory," he added. "This was a signal to the Syrians, that we will not be so forgiving of everything that lands in a territory." The source stressed that as of now, Israel and Syria were not a in a conflict situation.

The IDF is currently on standby for a security deterioration on both the northern front and the border with Gaza.

Israel warns Syria against spillover

Just hours earlier, Defense Minister Ehud Barak threatened 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.

"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 said, without elaborating, in an interview with Army Radio.

At the Sunday Cabinet meeting, Prime Minister Benjamin Netanyahu said that Israel was closely following events along the Syrian border, and was prepared for all possibilities on that front.

Home Front Defense Minister Avi Dichter said Israel needed “nerves of steel” to deal with the instability in Syria. He added that there was nowhere for Israel to respond, due to the chaos over the border.

The incidents “require a level-headed response from Israeli authorities,” Dichter said.

Sunday's scuffle came a week after three Syrian tanks entered the demilitarized zone on the Golan Heights on Saturday afternoon, and remained there for several hours into the evening.

The tanks, which were involved in heavy clashes with Syrian rebels, encroached the decades-old cease-fire agreement between Jerusalem and Damascus.

Turkey has retaliated against errant mortar shells and violent spillover from Syrian infighting in recent weeks as well.