Israel's command of Iranian air space leaves few obstacles in the way of its expanding bombardment, though it will struggle to deal a knock-out blow to deeply buried nuclear sites without the U.S. joining the attack, experts say.
While Iran has responded with deadly missile strikes on Israeli cities, Israel has shown its military and intelligence pre-eminence as its warplanes have crisscrossed the Middle East, hitting Iranian nuclear installations, missile stockpiles, scientists, and generals - among other targets.
On Monday, several Israeli officials declared the establishment of air superiority over Iran. The military likened its control of Iranian skies to its command of the air space over other arenas of conflict with Iran-aligned enemies, such as over Gaza and Lebanon - where Israel continues to bomb at will.
Prime Minister Benjamin Netanyahu said on Monday Israel's control of Iranian air space was "a game-changer". National Security Adviser Tzachi Hanegbi said pilots could operate "against countless more targets" over Tehran, thanks to the destruction of "dozens and dozens" of air defence batteries.
But even as Israeli officials laud the damage done so far, some publicly acknowledge Israel won't be able to completely knock out Iran's nuclear program - unless the U.S. joins the campaign with strategic bombers that can drop ordnance with the potential to penetrate sites buried deep underground.
Andreas Krieg, a senior lecturer at the School of Security Studies at King's College London, said Israel had achieved "quite a lot of operational and tactical successes ... But translating that into a strategic success will require more than what air power can deliver".
Krieg said even the heaviest U.S. bunker-busting bombs might struggle to penetrate Iran's deepest sites - in the event President Donald Trump decides to join the attack - suggesting special, commando-style forces might be needed on the ground.
Nevertheless, "Israel can act with impunity now, and they can do that in the way they did in it in Lebanon".
Israel launched its campaign on Friday, saying Tehran was on the verge of building a nuclear bomb - something Iran has always denied seeking from its uranium enrichment program.
While the Iranian military says it has downed Israeli warplanes, Israel denies this and says no crews or planes have been harmed during their missions to Iran, a return journey of some 3,000 km (2,000 miles) or more.
A senior Western defence source said Israeli warplanes have been refuelling over Syria - a bastion of Iranian influence until Bashar al-Assad was toppled in December. Israel is now operating over Syria with "near-total freedom", the source said.
ECHOES OF LEBANON
Israel's assault bears echoes of last year's devastating offensive against Hezbollah in Lebanon, during which Israel wiped out the Tehran-aligned group's top command - including its leader Hassan Nasrallah - within the first days.
Two U.S. officials told Reuters on Sunday that President Donald Trump had vetoed an Israeli plan in recent days to kill Iran's Supreme Leader Ayatollah Ali Khamenei.
Netanyahu on Monday did not rule out targeting Khamenei, saying doing so would end the conflict.
Further echoing its 2024 campaign in Lebanon, the Israeli military on Monday issued an evacuation warning for a specific area of Tehran, saying in a post on X that it planned to target the "Iranian regime's military infrastructure" in the capital.
A regional intelligence source said Israel had built a "truly surprising" network of agents in Tehran, likening the targeted killings of top officials to the blows directed at Hezbollah's leadership. The source said Israel's ability to "penetrate Tehran from the inside" had been astonishing.
Justin Bronk, a senior research fellow at the RUSI think-tank in London, said Iran has "few technical answers" to the combination of Israeli F-35 aircraft capable of waging electronic warfare against its anti-aircraft systems, supported by F-16s and F-15s carrying precision-guided ballistic missiles.
Though Israel was long assessed to have the upper hand, the speed, scale and effectiveness of its strikes - particularly against top Iranian generals - caught many off guard, said Barin Kayaoglu, a Turkish defence analyst. Iran's military appeared to have been "sleeping at the wheel", he said.
However, he cited challenges for Israel, saying its air force could find it difficult to maintain the current tempo of its operations because of the need to replenish ammunition stocks and maintain warplanes.
WEAPONS SHIPPED
In April, Israeli media reported an unusually large shipment of bombs arriving from the U.S. An unsourced report by public broadcaster Kan on April 17 said the delivery included hundreds of bombs, among them bunker busters.
Iranian air defences were damaged by Israeli strikes during exchanges of fire last year, Israeli officials said then. As last week's attack began, Israel said Mossad commandos on the ground in Iran destroyed more of Iran's anti-aircraft systems.
Despite Israeli air supremacy, Israeli officials have acknowledged that Iran's nuclear program cannot be disabled entirely by Israel's military, emphasising goals that fall short of its total destruction.
A former senior Israeli security official told Reuters that while U.S. military support was needed to do damage to Iran's most deeply buried facility, the Fordow enrichment plant, Israel was not counting on Washington joining the attack.
Israel has said it has not targeted Fordow - built beneath a mountain south of Tehran - to date, rather just the installations at Natanz and Isfahan.
Either way, the former official said Israel had already done enough meaningful damage to Iran's nuclear program, declining to be named so he could speak freely about sensitive matters.
If after the conflict ends Iran retained a residual uranium enrichment capability but not the people and facilities to do anything of concern with it, then this would be a major achievement, added the official.
Trump has repeatedly said Iran could end the war by agreeing to tough restrictions on its enrichment program.
Emily Harding from the Washington-based Center for Strategic and International Studies said conventional wisdom held that Israel could not completely eliminate the deepest buried parts of Iran's nuclear program.
"But Israel has strongly hinted that it has more capability than that conventional wisdom would suggest. For example, the ability to operate freely over the target allows for multiple sorties that could do a lot of damage," she said.
