Israeli officials have suggested in comments to the press that they see attacking Syria as a low-risk venture that probably won’t lead to any retaliation of any kind. Western officials are less confident.
With the Syrian military caught up in fighting its civil war, the fear among Western officials is that retaliation could come in the form of terrorist attacks targeting Israeli sites or Israeli tourists in other countries, with Hezbollah’s network likely to facilitate such a strike.
There is also the report that the Assad government has officially green-lit the Popular Front for the Liberation of Palestine (PFLP) to launch strikes on Israel. The group is downplaying the report, however, saying it is more “symbolic” than anything.
The PFLP was in control of a Palestinian refugee camp in Damascus before the war began, but it was lost to rebel fighters. The group doesn’t seem to have much of a following in the occupied territories for launching such strikes – which it seems they don’t intend to do at any rate.