Some speculate that the Israeli airstrikes in early May were tied with a message to the Iranians. A less conventional reason is tied to the operational/tactical reasons for the strike: to send a message to the U.S., the U.N., and anyone else that has called for restraint against significant intervention, citing sophisticated Syrian air-defenses as a chief reason. Israel just proved to the world that the Assad regime is but a shell of its former self and cannot protect its own airspace. A no-fly zone and/or an airstrike, therefore, is back on the table.
Some have wrongly speculated that this is the beginning of an alliance between the rebels and Israel. But the “enemy of my enemy is my friend” argument does not hold water here. Israel has had a relatively stable informal security understanding with the Assads, granted, with some flare-ups every now and then and it would much rather deal with the “devil you know” than something far more unstable and unpredictable.
The truth is that there are no good options in Syria. Do nothing and the war drags on indefinitely. Funnel money, arms and training to the rebels, the best fighters of which have ties to al-Qaeda, and blowback is inevitable. There are also reports of Russia considering equipping the Syrian regime with sophisticated anti-aircraft systems, helping rule out Western intervention. Israel has conveyed that it would consider destroying such shipments before they reach the regime’s forces.
Israel has a long history of preemptive attacks to set back weapons programs, facilities, convoys, etc to protect its very survival. This strike is a continuation of its policy to prevent weapons systems from getting into the hands of its enemies that are capable of striking the country. Given the fact that Hezbollah has formally committed to the Assad regime’s survival, count on Israel continuing with the status quo: not involving itself in an all-out war, but conducting limited strikes if it feels its security is being threatened.