Iran's supreme leader is facing a backlash from members of his own regime amid the escalating conflict between Israel and the Islamic Republic. Israel unleashed airstrikes across Iran for a third day on Sunday (June 15), with critical oil, gas and nuclear facilities hit.

Iran has retaliated with strikes on Israel, killing at least 13, including children. Tehran said on Saturday (June 14) that 78 people had been killed and over 320 wounded. The Middle East is braced for a protracted conflict after Israel's surprise bombardment of Iran's nuclear and military sites, which killed top generals and nuclear scientists.

Iran's Supreme Leader Ayatollah Ali Khamenei faces mounting anger from his regime's inner circle, with some questioning the Republic's handling of the crisis.

In private text messages shared with the New York Times, some Iranian officials have been asking how Iran's air defences weren't more effective in the face of Israel's attacks. The same publication reports Iran miscalculated by not anticipating attacks by Israel before talks with the US in Oman, which were supposed to take place on Sunday (June 15) but were called off.

On the attacks, one Iranian official asked: "Where is our air defence?" Another questioned: "How can Israel come and attack anything it wants, kill our top commanders, and we are incapable of stopping it?"

Hamid Hosseini, who is a member of an energy committee at Iran's Chamber of Commerce, said Israel's attack had completely caught the leadership by surprise, particularly the killing of top military figures and nuclear scientists.

He said: "It also exposed our lack of proper air defence and their ability to bombard our critical sites and military bases with no resistance."

Mr Hosseini also expressed concerns over Israel's ability to carry out secret operations targeting Iran's military and nuclear facilities.

Israeli security officials said the country’s Mossad spy agency smuggled weapons into Iran ahead of Friday’s strikes which were used to target its defences from within.

The officials said a base for launching explosive drones was established inside Iran and drones were activated during Friday’s attack to target missile launchers at an Iranian base near Tehran.

They said Israel had also smuggled precision weapons into central Iran and positioned them near surface-to-air missile systems. Strike systems had also been deployed on vehicles, with both activated as the strikes began, according to the officials.

In a recorded message to the nation broadcast as Iranian missiles flew toward Israel, Khamenei said the military was prepared to counterattack.

He said: "Don’t think that they (Israel) hit and it’s over. No. They started the work and started the war. We will not allow them to escape safely from this great crime they committed."

Israel's Prime Minister Benjamin Netanyahu urged Iranians to rise up against their country's "oppressive" regime, saying in a video posted on social media that Israel's actions were not targeted at them.

Sanctions and Tehran's handling of the economy have fuelled dissent across Iran. The hardline regime's morality police have also built up resentment among some Iranians.

Iran's moderate president, Masoud Pezeshkian, has called for unity in the face of Israel's attacks, saying his nation "needs togetherness, trust, empathy, unity and consensus".

Mr Pezeshkian has called for an end to Iran's isolation from much of the rest of the world and wanted a new accord on his country's nuclear ambitions.

But he has a battle on his hands with hardliners within the regime who are pushing a much more confrontational stance when it comes to the West.