From the Fiscal Times:
ISIS has been known for launching surprise attacks and opening new battlefronts when it seems to be losing. ISIS also has been criticized by many Arabs and Muslims for not taking its fight to Israel and instead fighting fellow Arabs and Muslims.
An attack aimed at Israel may boost ISIS’s popularity in the Arab world and refresh its recruitment and funding efforts.
On the other hand, some of ISIS’s top military commanders were former officers in Saddam Hussein’s army, and they may resort to what Saddam did in the 1991 Gulf War when he attacked Israel with mid-range rockets, hoping to drag the Israelis into a conflict that he was losing.
An Israeli retaliation in 1991 could have jeopardized the U.S-led coalition that then included Arab countries like Egypt, Syria and Saudi Arabia.
The same is true now. “It would be more likely a sign of desperation, as were Saddam's attempts to lure Israel into the 1991 war as a way of breaking the Arab coalition against him,” said NYU’s Levin.
At that time, continuous pressure from the first Bush administration and the installation of the Patriot anti-rocket system convinced the Israelis to refrain from reacting to Saddam’s attack.
Israel could launch a preemptive attack to destroy or significantly damage these ISIS-affiliated units whether by air or by ground forces. Israel used its advanced air force to launch attacks in Syria several times since the beginning of Syrian civil war in 2011.
Meanwhile, Israel has recently boosted its defenses in the Golan Heights, saying its main concern was to prevent any major weapon transfer from Syria to Hezbollah, the Lebanese guerrilla organization that has engaged in several rounds of war with the Israelis since the 1980s.