The fall of Bashar al-Assad is a historic moment for the Middle East. It’s too soon to know its full consequences. It is not too early to assert that the war Israel has waged against Iran and its proxies in the past year has yielded astonishing results. Hamas is decimated, Hezbollah degraded, Iran stymied, and now the Syrian tyrant has fled. Russia, the primary power behind Assad, retreats to the sidelines. What a hand for a new American administration.

And for Israel. Prime Minister Netanyahu, in televised remarks, called Mr. Assad’s fall the “direct result of our forceful action against Hezbollah and Iran, his main supporters. It set off a chain reaction of all those who want to free themselves from this tyranny and its oppression.” Mr. Netanyahu’s remarks were echoed on Sunday by President Biden, who described the events in Syria as a “direct result” of Israel and Ukraine defending themselves from aggressors.

What a contrast from the instinct for appeasement that Mr. Biden himself championbed. He rejected a military approach to Iran and pursued a diplomatic course as Iran pursued an atomic bomb. He sought cease fires at Gaza and Lebanon. The fact is that Mr. Biden’s list of “don’t”s had been followed by Israel, none of the advances we’re seeing today would have happened. It’s hard to imagine a clearer contrast in terms of policy.     

In the event, Israel killed Nasrallah in September at Beirut, along with the entirety of Hezbollah’s upper echelon. The world’s myopic obsession on how Israel levied the battle against Hamas at Gaza missed the scoop — that Israel and its foes were already fighting a regional war, which Israel is now winning. The loss of Syria for Russia and Iran is like losing a crucial chess piece — say, a rook — just when the match is set to enter a decisive stretch. 

The strategic losses for Moscow and Tehran do not alone ensure that the future of Syria will be less blighted than its past. The armies before whom Mr. Assad fled to Russia comprise veterans of Al Qaeda and the Islamic State. No wonder Israel has seized the Syrian side of Mount Hermon to create a buffer zone and get a clear view. Plus, too, Channel 12 in Israel reports that Israel carried out preemptive strikes on chemical weapons caches in Syria. 

It would be folly not to credit the rebels who have appeared in arms against Syria. So would the failure to mark Israel’s adroit use of hard power in accomplishing  regime change. What a contrast to, say, President Obama’s failure to enforce his own red lines in respect of Mr. Assad’s use of chemical weapons. What a tragedy that he and President Biden bet on an appeasement with Tehran that would have left the mullahs on top and in charge.

It could be that just as the Arab armies of 1967 invited their own destruction when they massed to attack Israel, so too the Iranian alliance will look back at October 7, 2023 as the day when their downfall began. Losing Tehran’s foothold in the Arab world leaves it diminished, as does Israel’s strikes on its weapons facilities. Thanks to the IDF, President Trump will enter office in a position to share the opportunities with the Syrian people. 

Support for the Kurds would be a good place to start, as would plans to frustrate Turkey’s designs to spread its baleful influence in the broken land of Syria. Now is the moment to deliver a knockout punch to the mullahs — or help the Israelis to do so. Those who have scoffed at Mr. Netanyahu have been proven wrong. Rotten regimes appear eternal, until they are proven to be ephemeral. The scenes at Damascus could soon preview a denouement at Tehran.