Why Assad’s Fall Made Israel’s Large-Scale Air War With Iran Possible

For roughly two decades, Israel has lobbied the United States to assist it in an air campaign aimed at destroying Iran’s nuclear program. Israel’s advanced air force lacked the range and secure lines of transit to sustain a large volume of strikes deep into Iran by itself.

Clearly that conventional wisdom had changed by this June 13 when the IDF initiated its large-scale aerial assault on Iran on, which Israeli Prime Minister Benjamin Netanyahu said will last at least two weeks. Why, after all these years, did Israeli leadership decide it could go it alone?

Undoubtedly, the Israeli Air Force (IAF) benefited from years of capability enhancements including standoff-range missiles like Golden Horizon, long range drones, a growing fleet of F-35I stealth fighters, installation of aerodynamically efficient conformal fuel tanks on fighters, and more air defenses system capable of battling Iran’s ballistic missiles.

But also critical was the collapse of the Syrian government of Bashar al-Assad seven months earlier.

Historically, sheer geography has made it difficult for Iran and Israel to war directly against each other—with around 600 miles of hostile Syrian and Iraqi airspace interposing themselves, buffering Iran from Israel’s regionally dominant air force. To circumvent these obstacles, Tehran gradually developed and began amassing medium- and intermediate-range ballistic missiles that could reach Israel.

Jet fighters lugging heavy ground attack weapons, with spare fuel reserved for possible combat maneuvers, can’t fly as far as maximum range specifications for ‘clean’ aircraft would imply. But the IAF could execute long-distances raids using its seven jetliner-based KC-707 Re’em tankers (and seven less capable KC-130Hs), as it did repeatedly in 2024. However, that range extension was constrained by the risks of pushing the vulnerable tankers too close to hostile air defenses.

Iraq’s air defense capability was destroyed by the U.S. in 2003, but Israeli jets still needed to enter Syrian airspace to get to Iraq. And alternate routes overflying Jordan and Saudi Arabia would involve angering relatively friendly states with air defense capabilities.

Still, Syria’s fall might seem unimportant given that Damascus’s large air defense system proved incapable of stopping roughly 14 years of continual Israeli airstrikes, managing to shoot down only one Israeli F-16 in 2018. The Israeli Air Force (IAF) basically wrote the book on modern suppression of enemy air defense (SEAD) tactics when it dismantled Syrian surface-to-air missile defenses in Lebanon in 1982 using a combination of fighters armed with standoff-range missiles, drones, and electronic warfare.

However, having to continually circumvent, overwhelm or selectively destroy Syrian air defenses still involved managing risks, and expenditures of resources and effort, reducing the ‘throughput’ the IAF could project against Iran itself.

Most importantly, Israel couldn’t risk sending its KC-707s into Syrian airspace as long as Damascus had active long-range, high-altitude missile systems like the S-200 and S-300 operational.

That reality changed when Bashar al-Assad’s government was abruptly overthrown by rebel forces last December. As Assad’s army evaporated, Syria’s air force and air defense apparatus became fully inactive. Though the new government was hostile to Iran, Netanyahu nonetheless had the IAF embark on an all-out bombing spree destroying most of Syria’s abandoned warplanes and high-altitude air defense systems (and it’s navy too), removing the new Syrian government’s ability to assert sovereignty, even ineffectively, over its airspace.

This opened a safe corridor for IAF tankers over Syria to accompany Israeli fighters and top them off right up to the edge of Iran’s air defense zone—a big effective boost in range for Israeli fighters.

Of course, not having to suppress both Syria and Iran’s air defenses simultaneously was an advantage. The corridor also improved Israel’s options for search and rescue of potential ejected pilots, and may have helped special forces insert into Iranian territory—and more pressingly, extract them after executing their surprise drone and missile attacks on June 13. Notably, two C-130 or KC-130H transport aircraft were recorded flying at low altitude over Syria that morning.

Such methods would have been more perilous if needing to traverse hundreds of miles of Syrian defenses too.

Iran’s loss of deterrence

Another factor behind Israel’s 2025 war was Tehran’s loss of military deterrence in 2024, of which the fall of Syria was the final and most shocking in series of major setbacks.

Before 2024, both Iran and its Lebanon-based ally Hezbollah had spent many years building up arsenals of long-distance missiles, drones and rockets–and it was uncertain how successfully Israel’s air defense system would cope against a large-scale onslaught.

The first disaster arose from Hezbollah’s modest-scale border attacks against Israel, begun to show support for Hamas in Gaza. This eventually led to massive Israeli retaliation, including detonation of rigged cellphones and radios furnished to Hezbollah’s leadership cadres, and a massive bombing campaign targeting Hezbollah arsenals and commanders, culminating in the assassination of its leader Hassan Nasrallah. Hezbollah proved unable to counter-escalate convincingly.

The other shoe fell when Iran launched two brief but large-volume long-distance attacks on Israel: first, 320 drones and missiles that April, and then 200 ballistic missiles in October. Though the defensive effort to stop these attacks—involving the U.S. and several other countries’ air forces and navies—was extensive and expensive, they were also largely successful at preventing major military damage or extensive loss of life in Israel.

Iran’s broadsides thus may have inadvertently led Israeli leaders to estimate Iran’s long-range strike capabilities as less capable than some had feared. (In the current war, Iran’s missile raids targeting Israel have been more lethal and destructive than those in 2024, though not massively so, so far.)

Furthermore, an Israeli counterstrike on October 26 destroyed Iran’s most sophisticated air defense systems—Russian-origin S-300s batteries—substantiating IAF confidence it could deal with Iran’s dense but dated air defenses.

Thus Tehran’s strikes may inadvertently have made it a less intimidating target. Then the unexpected collapse of Assad in Syria removed its buffer. And the election of Donald Trump meant the U.S. was more likely to support an Israeli attack on Iran, whether by agreeing to the war in advance, or by not punishing Israel for defying pressure not to attack.

Israel mauled Iran’s air defenses. Now what?

The IAF has established its ability to assail targets across western Iran, so far without evident aircraft losses. However, it lacks weapons capable of penetrating deep underground to destroy Iranian centrifuges in Natanz and Fordow. Some reports allege Natanz’s may have suffered significant damage due to loss of electrical power. True or not, Fordow—situated literally under a mountain—has sustained minimal if any damage so far.

Therefore, the centrifuges may vex Netanyahu’s war aims. Maybe the IDF has another rabbit to pull out of its hat—a secret weapon, or an improbably high-risk commando raid. Or Netanyahu may be hoping Iran’s retaliatory attacks trigger U.S. intervention, which could involve strikes by B-2 bombers armed with deep-penetrating GBU-57 bombs.

Netanyahu has also proclaimed the aim of regime change in Iran, or he might be satisfied by compelling policy concessions (as Tehran is already reportedly offering). Lastly, he may have a ‘mow the lawn’ concept for sustaining persistent attacks on Iranian efforts to rebuild nuclear facilities and ballistic missile assets beyond the scope of the current campaign, much as the IAF continually bombed Syria for over a decade.

However, geography may pose problems to a long-term bombardment concept due to Iran’s ‘strategic depth’, with territory extending over 800 miles east of its border with Iraq. Tehran might attempt to rebuild facilities and reconstitute forces in eastern Iran, where Israel’s strike capacity remains much more limited.

While Assad’s fall gave Israel a corridor by which to defy the tyranny of distance, key metrics—whether of aircraft fuel capacity or meters of soil and bedrock over subterranean centrifuges—will continue to shape its war with Iran.