The Israel Air Force attacked an abandoned ISIS military facility in the Syrian Golan Heights early Monday in response to the mortar and gunfire aimed at an IDF patrol from that area the previous day, dropping 10 one-ton bombs on the target.
There were no immediate reports of injuries.
The target, an outpost in Wadi Sirhan not far from the border with Israel, was previously used by the UN. International forces abandoned the outpost two years ago after fighters from Shuhada' al-Yarmouk (the Yarmouk Martyrs Brigade), which is affiliated with ISIS, kidnapped UN peacekeepers.
It has since been taken over by the militants and serves as a base of operations near the border with Israel. The outpost is used for training and to store arms.
"This is a follow-up attack to the one carried out yesterday (Sunday), meant to prevent the terrorists from returning to the facility, which constitutes a substantial threat in the area," the IDF Spokesman's Office said in a statement.
The skirmish began on Sunday when a unit of the IDF's Golani Brigade was in the middle of an ambush operation near the border fence not far from moshav Nov.
The soldiers came under fire by the terrorists from a heavy machine gun-mounted vehicle.
Shortly after the gunshots were reported, prompting the soldiers to return fire, a number of mortar shells were also fired in Israel's direction from the Syrian side of the Golan Heights which landed near the security fence. Moments later, the IAF reported it had killed all four terrorists.
Following the skirmish on Sunday, the IDF raised the alert level across the Israel-Syria border—from Hamat Gader near the Sea of Galilee to the Hermon Mountain in the northern part of the Israeli Golan.
There are hundreds of Yarmouk Martyrs Brigade militants in the area who fight the Syrian regime and the Nusra Front group (affiliated with al-Qaeda) from time to time.
The incident breaks with usual patterns of similar incidents which have taken place over recent weeks in which fighting between rebel forces and the Syrian regime is usually presumed to be the cause of stray mortars and bullets, rather than deliberate attacks by ISIS terrorists.
Nevertheless, the assault on Israeli territory does come against a background of renewed fighting between rebel forces and the Syrian army commanded by President Bashar Assad.
Indeed, on Saturday rebel forces announced an operation designed to lift the regime’s siege on areas controlled by the rebels.