US President Donald Trump’s March 29 declaration that he is leaving the crisis in Syria to “other people,” and the summit of Russian President Vladimir Putin, Turkish President Recep Tayyip Erdogan and Iranian President Hassan Rouhani just a few days later, on April 4, vividly demonstrate the grave changes taking place in the region — for Israel as for others.

Following the new situation in Syria and the American inclination to withdraw from the region, Israel needs to take in the very near future several security steps. With or without American backing, Israel must prevent at all cost Iranian entrenchment in Syria: no bases for the Iran Revolutionary Guard Corps, for Hezbollah or for Shiite militias, and the zone west of the Suwayda-Damascus highway should be strictly demilitarized.

Indeed, these necessary military steps by Israel may bring about escalation. But past experience teaches us that acquiescence to Iran’s presence will bring far more costly results.

A war on Israel’s northern fronts may inflict heavy damage on its civilian population. That's why it is better to prevent such an escalation. This could be achieved only by abandoning the old, inefficient equation, in favor of a new deterrence equation. Israel's warnings that it would destroy Lebanese infrastructure if Hezbollah rains down missiles on its cities do not deter anyone in Tehran. No one in the ayatollah regime cares if Lebanese Sunnis, Christians or even Shiites go without water or electricity. Hence, Israel must make it clear that if its cities are attacked, it will retaliate by targeting Iran’s oil export installations. There are ways to give this equation credibility. Hollow deterrence does not work.