Almost the entire Syrian side of the Golan Heights is now under the control of rebel forces, including radical Islamist groups, a senior Israeli military commander in the area said Friday.

Only the Quneitra border area is still in the hands of forces loyal to President Bashar Assad, Lt.-Col. Anan Abbas, deputy commander of the Golan Brigade, told Israel’s Channel 10. About 95 percent of the Syrian side of the Golan is in the hands of anti-Assad rebels, including radical Islamic groups such as the Al-Nusra Front, affiliated with al-Qaeda, a rival of the burgeoning Islamic State of Iraq and the Levant, better known as ISIL or ISIS.

One of two Syrian army brigades that used to control the area has completely disappeared, the officer said.

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At present, the Islamist groups in the area are focused on the war against Assad, he said, “but we know their goal is to harm Israel; we’ve seen their propaganda material.”

The Israeli officer said that the dramatic gains made by the rebel forces in the area appeared to explain why Syrian troops fired a missile on Sunday that killed a 15-year-old boy on the Israeli side of the border.

Apparently forces loyal to Assad, stationed some five kilometers inside Syrian territory, erroneously calculated that a civilian truck, delivering water to Israeli contractors who were working on the border fence, was actually a rebel truck on the Syrian side of the border, and opened fire on it with an anti-tank missile. The attack killed 15-year-old Mohammad Karkara, who had accompanied his father, a civilian contractor, to work that day.

In response to the attack, Israel that night launched a series of retaliatory air strikes that killed a reported 10 Syrian soldiers, though Damascus put the number at four.

Subsequently, the TV report said, Syria conveyed the message to Israel, via UN liaison personnel stationed on the Golan, that the anti-tank missile was fired in error. Israel “is inclined to accept the explanation,” the report said.

The Golan Heights is a strategic plateau on the Israeli-Syrian border. Israel captured the territory in the 1967 war, having been attacked from the Golan over the previous 20 years, and extended Israeli law to the area in 1981. Unsuccessful peace efforts over the years have seen Israel ready to trade most of the Golan for a permanent accord with Damascus, but the notion of Israeli-Syrian peace has all but disappeared as Syria collapsed into anarchy over the past three years of civil war.