Israel has issued a stern ultimatum to Iran if the country decides to retaliate for its airstrikes on Tehran early Saturday morning.

Israel hit Iran with three waves of attack, focusing on 'missile manufacturing facilities' it claimed were used to produce the missiles that Iran fired at the Jewish nation on October 1.

It also struck 'surface-to-air missile arrays and additional Iranian aerial capabilities, that were intended to restrict Israel’s aerial freedom of operation in Iran,' the IDF announced.

But if Iranian officials were to strike back, Israel would be 'obligated to respond,' Rear Adm. Daniel Hagari warned in a video posted to X.

'Our message is clear: All those who threaten the state of Israel and seek to drag the region into a wider escalation will pay a heavy price,' he said. 'We demonstrated today that we have both the capability and the resolve to act decisively, and we are prepared on offense and defense, to defend the state of Israel and the people of Israel.'

IDF forces had earlier announced on social media it was conducting 'precise strikes' on military targets in Tehran in response to what it called 'the continuous attacks from the regime in Iran against Israel.'

Several hours later, the Israeli military announced that it has completed its strikes on the Iranian capital, saying: 'Our planes have safely returned home. The retaliatory strike has been completed and the mission was fulfilled.'

Israel hit Iran with three waves of attack on Saturday morning. The first focused on Iranian air defense systems, while the second and third focused on missile and drone bases as well as production sites, according to Axios reporter Barak Ravid. 

The strikes hit roughly 20 sites over the course of the night, according to the New York Times. 

Iranian officials later said those strikes caused only 'limited' damage, claiming 'the attack has been successfully intercepted and countered' by Iran’s 'integrated air defense system,' its state-run news agency IRNA reported. 

It had earlier said that several 'loud explosions' that were heard across the city were related to the country's air defense systems. 

The National Air Defense Headquarters went on to say the Israeli strikes were a 'provocative attack,' but made no mention of a possible response, just saying, 'The scope of this incident is currently under investigation,' NBC News reports. 

A correspondent for Beirut-based Al-Mayadeen had also reported explosions on the outskirts of Diyala and Salah al-Din in Iraq, the outlet posted to X, while others claimed there were explosions in Damascus, Syria as well. 

The Israeli strikes came in retaliation for Iran's attack on October 1, in which around 200 ballistic missiles were fired at Israel - in Iran's second direct attack on Israel in six months. 

While many of the missiles were shot down, dozens managed to strike the Nevatim airbase, demonstrating that Iran could at least partially penetrate Israel's sophisticated air defence systems at some of the country's most highly protected sites. 

Iran claimed they were in response to an Israeli attack that killed IRGC operations commander Brig-Gen Abbas Nilforoushan and Hezbollah leader Hassan Nasrallah in Lebanon.

An Israeli military statement said that Israel 'has the right and the duty to respond.

'The regime in Iran and its proxies in the region have been relentlessly attacking Israel since Oct. 7 - on seven fronts - including direct attacks from Iranian soil,' it said.

The strikes finally came just as U.S. Secretary of State Antony Blinken was arriving back in the U.S. after a tour of the Middle East where he and other U.S. officials had warned Israel to tender a response that would not further escalate the conflict in the region and exclude nuclear sites in Iran. 

Amid the attack Hagari called on the people to be 'alert and vigilant'.

Soon after, communities in northern Israel were told to take shelter amid an alert of a drone from Lebanon.

The Home Front Command issued an alert for a 'hostile aircraft intrusion' around the northern city of Nahariya and other parts of Galilee. 

Prime Minister Benjamin Netanyahu and Defense Minister Yoav Gallant were in a bunker at the military headquarters in Tel Aviv, Netanyahu's office said.

Iranian authorities have warned Israel against launching an attack, saying any strike on Iran would be met with a stronger retaliation.

Officials, under the condition of anonymity, told the New York Times that Iranian supreme leader, Ayatollah Ali Khamenei, has told his armed forces to prepare several responses to be implemented depending on the severity of Israel's strike.

Widespread damage and a high number of casualties could provoke a sharp reaction from Tehran, the officials said, adding there may be no response if the attack is limited to military compounds.

A major attack, meanwhile, would trigger a response with as many as 1,000 ballistic missiles - fivefold the number used earlier this month in what was its largest attack on Israel in its history.

The Ayatollah has allegedly ordered that such a heavy response should be carried out if Iran hits energy infrastructure or nuclear facilities, or assassinates senior officials, the officials said.

Yet Iran has maintained that it does not seek escalation, but has sent out persistent warnings to Israel that it will 'not last long' as it presses on with operations in Lebanon and Gaza. 

U.S. President Joe Biden had also warned that Washington, Israel's main backer and supplier of arms, would not support a strike on Tehran's nuclear sites and has said Israel should consider alternatives to attacking Iran's oil fields.

According to Fox News, the White House was notified shortly before Israel conducted the strikes, however officials have said the US was not involved in the operation.

But a senior White House official later revealed that Biden worked directly with Israeli Prime Minister Benjamin Netanyahu 'to design a response that served to deter further acts against Israel while reducing risk of further escalation.'

The official also claimed the White House 'worked with the Israelis over recent weeks to encourage Israel to conduct a response that was targeted and proportional with low risk of civilian harm.'

This comes as state news agency SANA reported that Syrian air defences intercepted 'hostile targets' near Damascus, as Israel said it was launching strikes in Iran.

'Our anti-aircraft defense is confronting hostile targets in the skies around Damascus,' SANA said on Telegram after reporting 'sounds of explosions' in the vicinity of the Syrian capital.

International flights began diverting around western Iran as news of the strikes broke, flight-tracking data showed. 

Iran later announced it has closed its airspace until 8:30am Israel time - for more than four hours.

And as the region appears to be on the brink of war, the Israeli military boasted that the decapitation of Hezbollah was 'not the end of our toolbox' and gloated that they can 'reach' anyone who threatens them. 

In a brazen taunt to the countries surrounding them, the Israel Defence Forces (IDF) then shared a diagram of the Hezbollah chain of command, where each leader had been marked up as 'Eliminated'. 

On top of this, three days ago Israel killed  Hashem Safieddine, the alleged 'next leader' of Hezbollah in a blitz of his bunker. 

Safieddine was a powerful cleric within the Hezbollah ranks and was anticipated to succeed Hassan Nasrallah. 

About 25 other Hezbollah leaders were also reportedly killed during the airstrike.