The Israel Defense Forces fired a warning shot 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.

The missile fired by the IDF was a Tamuz, an anti-tank missile with a range of 25 kilometers. The IDF's use of the Tamuz was first made public last year, although it has actually been in use by the IDF since the 1980s. The Tamuz was used both in the Second Lebanon War and Operation Cast Lead in Gaza.

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 northern Israeli community 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.

Defense Minister Ehud Barak earlier Sunday 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.

"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 in an interview with Army Radio, hours before the incident.

Prime Minister Benjamin Netanyahu, also speaking before Sunday's mortar strike on the Golan, told his cabinet that Israel was "closely following what is happening on our border with Syria and [is] prepared for any development".

Israel last week warned 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.

Three other Syrian mortar shells strayed in the Golan Heights last Thursday, one of which landed on the fence of an Israeli community without exploding. Just a week before that, Israel complained to the United Nations after three Syrian tanks entered a Golan demilitarized zone. Israel also said a stray Syrian bullet hit one of its army jeeps while on patrol.

Israel has tried to stay out of the 19-month Syrian insurgency, reluctant to be drawn into another war and unclear about whether a post-Assad Syria might prove more hostile.

But Barak said last week that he hoped the rebels would win, that Assad would fall, and that "a new stage in the life of Syria will begin."

IDF Chief of Staff Benny Gantz, meanwhile, warned troops on the Golan Heights a week ago: "This is a Syrian issue that could become our issue."

The Tamuz is equipped with an electro-optic sensor that allows the team operating the missile to monitor the target during the projectile's flight and guide it accurately all the way to the point of impact.

During the Second Lebanon War in 2006, the Tamuz missile saw extensive action, with some 600 missiles of the type fired, mostly in support of ground forces. Even though the strikes were accurate, in the lessons learned after the war, it was decided that in at least half of the cases there was no operational justification for the use of this accurate but expensive missile. With the cost of every Tamuz coming to some NIS 500,000, their use in the Second Lebanon War cost NIS 300 million.

Watch: A Tamuz missile hits the window of a house during the Second Lebanon War

Open gallery view A Tamuz missile fired by the IDF last year. Credit: Ilan Assayag