A battle between Syrian rebels and forces backing Bashar al-Assad ended on Wednesday with militants taking control of a portion of the strategic Golan Heights near the Quneitra border crossing with Israel.

“The Britain-based Syrian Observatory for Human Rights said an array of rebel fighters, including from the al-Qaida-linked Nusra Front and the Western-backed Free Syrian Army, took the crossing after heavy fighting that left at least 20 Syrian soldiers and an unknown number of rebels dead,” the Associated Press reported.

The indication that pro-Western rebels and Islamist militants apparently worked together to seize this area is likely to frustrate President Barack Obama’s efforts to shore up support for limited military strikes in Syria aimed at targeting Islamic State militants and providing support for moderate opposition forces.

For Western military planners, though, al-Nusra does not pose the same threat to the West as does the Islamic State even in spite of its links to al-Qaeda. The group’s decision to release an American hostage after nearly two years of captivity indicated to some observers that the group can be negotiated with and is seeking to present itself as a more moderate Islamic militia than ISIS.

If assuaging the West’s apprehensions was a goal shared by the Free Syrian Army, though, they did not accomplish that feat. A spokesman for pro-Western opposition forces told reporters that their presence on the Israeli border poses no threat to the Jewish state… for the moment.

“Our aim isn’t Israel right now, and we in the FSA haven’t targeted Israeli lands,” said militant spokesman Kenan Mohammed. “The matter of Israel — it’s not for now, and it’s more political.”

That is going to serve as little comfort to Israel. On Wednesday, IDF forces exchanged fire with Syrian army as fire from their battle with rebel militants spilled over the border.

“Israel Defense Forces gunners launched artillery at a Syrian army position, in response to the fire that lightly-to-moderately wounded an IDF officer along the border, as the battle between rebel and regime forces trickled into Israel,” Haaretz reported.

The IDF holds the Syrian army responsible for the incident and for the round of mortar shells that landed in Israel after hours of heavy battle between the rebels and armed forces loyal to President Bashar Assad.

The army has declared the area around the crossing and Mount Bental as a closed military zone. According to witnesses, a part of the border crossing has caught fire, including on the Israeli side of the Golan Heights, as have landed in agricultural fields on Israeli territory.

The exact identity of the rebels fighting near Quneitra remains unclear. Observers surmise they either belong to the Free Syrian Army or the Islamic Front, and it is not the first time they have tried to take control of the area.

This latest development in the ongoing Syrian civil war unlikely to mollify American anxiety about intervening in Syria, even though the targets are narrowly defined and geographically isolated.