IDF ground forces fired a warning shot at the Syrian military on Sunday for the first time since the 1973 Yom Kippur War.They shot the guided missile after a stray Syrian shell from civil strife in that country exploded on the Golan Heights for the second time in recent days.The shell hit as Israel suffered a barrage of missiles from Gaza, putting the IDF in the position of monitoring enemy fire along both the northern and southern borders.Tovah Lazaroff and Jerusalem Post staff contributed to this report.“In the midst of Syrian infighting, a mortar shell fired by the Syrian Army struck near an [IDF] outpost at Tel Azeka,” IDF spokesman Brig.- Gen. Yoav Mordechai said.The shell failed to cause injuries or damage. It was one of a series that hit 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.The IDF fired an advanced Tapuz-type missile at a Syrian artillery cannon, military sources said. Concurrently, Israel sent a warning message to the UN, saying that any further firing into Israel will result “in a real response.”The IDF limited its return fire to a single missile, 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 shell 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 in a situation of conflict.The IDF is on standby in case of security deterioration on both the northern front and on the border with Gaza.Defense Minister Ehud Barak told Army Radio, “The message has certainly been relayed. To tell you confidently that no shell will fall? I cannot. If a shell falls, we will respond.” On Syria, Barak said: “After a number of shelling incidents into Israeli territory during recent weeks, I instructed the IDF to respond in-kind should the situation recur. Today, another mortar shell was fired from Syria, landing on an IDF outpost. The Chief of Staff ordered the IDF to return fire on the mortar outpost [from which the mortar was fired]. This was a sign to Syria that we will not tolerate shelling into our territory.”A complaint was also lodged with UNDOF.Syria has been in the midst of a brutal civil war for over a year, and the IDF has been instructed to prevent the battles from spilling over into our territory.Additional shelling into Israel from Syria will elicit a tougher response, exacting a higher price from Syria.Strategic Affairs Minister Moshe Ya’alon told Arutz 7 that Israel has sent very clear messages to Syria not to let the violence spill over into Israel. He added that he believed Syrian President Bashar Assad understood the importance of keeping the border quiet.At Sunday’s cabinet meeting, Prime Minister Binyamin Netanyahu said that Israel was closely following events along the Syrian border, and was prepared for all possibilities on that front.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 decadesold cease-fire line Turkey has retaliated against errant mortar shells and violent spillover from Syrian infighting in recent weeks as well.