JERUSALEM — The Israeli military said it had killed four militants linked to the Islamic State on Sunday after they attacked Israeli forces in the Golan Heights.
The confrontation appeared to be the first of its kind between Israel and Islamic State-affiliated forces based in Syria. It was not immediately clear if the militants’ attack was spontaneous or if it signaled a possible change of policy by extremist groups.
Lt. Col. Peter Lerner, a spokesman for the Israeli military, described the exchange as “unique” in magnitude. He said that jihadist fighters, riding in a vehicle with a machine gun mounted on its roof, had assaulted an Israeli reconnaissance unit with gunfire and mortars as its members lay in waiting on the Israeli-controlled side of the contested territory.
Prime Minister Benjamin Netanyahu of Israel said the soldiers had “successfully repelled an attempted attack on the triangle of borders,” referring to the point where Israel, Syria and Jordan converge. Using the Arabic acronym for Islamic State, he added, “We will not let Daesh elements or other hostile elements use the cover of the war in Syria to establish themselves next to our borders.”
Israel has generally tried to keep out of the Syrian civil war, declaring neutrality in the struggle between President Bashar al-Assad and rebel forces. But Israel has carried out a covert campaign to prevent the transfer of sophisticated weapons from Syria to Hezbollah, the Lebanese Shiite militant group that is aiding Mr. Assad. And whether intentionally or not, the fighting in the Syrian Golan Heights has occasionally spilled over into the Israeli-held part.
Israel and Hezbollah-affiliated militants have exchanged fire, and Israel has acknowledged retaliatory strikes against Syrian government positions. Israel has also been extending medical and other humanitarian aid to what it describes as more moderate rebels across the border.
Until now, though, there had been little direct engagement with the jihadist forces who control the southern section of the frontier with Syria and have pledged allegiance to the Islamic State, also known as ISIS or ISIL.
The ambush on Sunday occurred in a pocket of land between the Israeli-constructed security fence and the decades-old armistice line that serves as a border, Colonel Lerner said. He gave no specific reason for the mission, but said the military’s activities in the area were based on threat assessments and were intended to maintain Israeli sovereignty west of the border.
“They have said they will come to Jerusalem,” Colonel Lerner said of Islamic State, whose various branches have issued such threats in the past. “We have no intention of letting them come to Jerusalem.”
Around 9 a.m., he said, gunmen from an Islamic State-affiliated group — the Yarmouk Martyrs Brigade, which recently linked up with, or changed its name to, the Army of Khalid Ibn al-Walid, according to local experts — opened fire at the Israeli forces and the forces responded. In the ensuing exchange, the militants launched mortars at the Israeli soldiers, the air force was called in and the vehicle carrying the fighters was hit by an airstrike, killing its four passengers.
Nitzan Nuriel, a former director of Israel’s counterterrorism bureau, said that since the Second Lebanon War in 2006 Israel had acted, based on intelligence, in what he called the “gray area” between the Israeli security fence and the official boundary lines separating Israel, Lebanon and Syria. The militants’ decision to open fire was probably made locally, not from above, Mr. Nuriel told reporters on Sunday.
“I believe the message was strong enough and simple enough: We do not cross the border, and if you open fire at us you will pay the price,” Mr. Nuriel said. With the jihadists’ efforts focused on fighting Mr. Assad and his Hezbollah allies, he said, opening a new front against Israel was “the last thing ISIS needs at this stage.”
But Israeli security officials have long said that it was only a matter of time before the Islamic State-affiliated forces along the Syrian frontier turned their attention to Israel.
Amos Yadlin, a former Israeli military intelligence chief who now directs the Institute for National Security Studies at Tel Aviv University, said it was too early to say whether the clash represented a change in strategy by Islamic State-affiliated forces.
If there has been a change, Mr. Yadlin told reporters, it may have been prompted by the need for “some propaganda element, some sympathy in the Arab world.” He said of the Islamic State, whose strongholds in Iraq and Syria are under assault: “They are under pressure everywhere.”