Islamic State loyalists in Syria have made attempts in recent weeks to expand the extremist group’s territory near the border with Israel, but have been twice thwarted by Syrian rebels along the Golan Heights. Israel has not yet responded to the incidents, even as mortar shells from the battles with ISIS fighters landed across the border into Israeli territory, Israeli news site Ynetnews said.

In the past, Israel has increased its forces in the Golan Heights near the Syrian border when shells fired by the Syrian army spilled over into Israeli territory, the Jerusalem Post said. However, Israel has remained quiet during the past two weeks as rebel fighters from Syria repelled militants loyal to the Islamic State group, also known as ISIS or ISIL.

The ISIS-loyalists have so far failed to gain foothold on the Golan Heights border, which would allow the Islamic State to set up a base for operations against Israel, Ynetnews said. Their attacks have been thwarted by the Free Syrian Army, which reportedly receives Israeli humanitarian aid, in cooperation with the Nusra Front, a Sunni Muslim branch of al Qaeda operating in Syria and Lebanon.

Israel views al Qaeda-affiliated groups as enemies but is far more hostile with Iran and its allies. Earlier this year, Israel opened its borders with Syria to provide medical treatment to the Nusra Front and al Qaeda fighters wounded along the Golan Heights, the Wall Street Journal said.

Nusra Front, which has referred to the United States and Israel as enemies of Islam, is fighting the Iranian-backed alliance of Syrain President Bashar Assad and Hezbollah. Nusra Front seized the border area last summer but hasn’t attacked Israel.

“There is no doubt that Hezbollah and Iran are the major threat to Israel, much more than the radical Sunni Islamists, who are also an enemy,” Amos Yadlin, the former head of Israel’s military intelligence, told the Wall Street Journal in March. “Those Sunni elements who control some two-thirds to 90 percent of the border on the Golan aren't attacking Israel. This gives you some basis to think that they understand who is their real enemy—maybe it isn’t Israel.”