Tehran, Iran – Iran has been biding its time since the July 31 assassination of Hamas politburo chief Ismail Haniyeh in Tehran.

The high-profile assassination will beget Israel vengeance, Supreme Leader Ayatollah Ali Khamenei and other top political and military officials have promised, as a “guest” dear to Iran and its “axis of resistance” was killed on Iranian soil.

The manner of Haniyeh’s and his bodyguard’s killing also raised many eyebrows, as they are believed by Iranian armed forces to have been targeted with a projectile – likely a relatively small, anti-armour guided missile – fired from not too far outside their residence for foreign dignitaries in affluent northern Tehran.

The fact that Israel is now pounding Lebanon, its civilians and infrastructure to devastating effect, supposedly only to target Hezbollah, a prominent member of the Iran-led “axis of resistance”, merely ramps up pressure on Iranian leaders to take a more direct retaliatory approach.

The Israeli military has killed at least 620 people and wounded thousands more across Lebanon in the past four days, with at least 72 killed on Wednesday, according to the Lebanese Ministry of Public Health. The attacks have been the deadliest Lebanon has seen since the end of its civil war close to 35 years ago.

The thousands of bombs that have been dropped over Lebanon by a fleet of Israeli aircraft have also destroyed many homes and other civilian infrastructure, displaced tens of thousands, and killed paramedics and journalists.

Is Iran’s timeline changing?

Iran has continued to exercise restraint as Israeli Prime Minister Benjamin Netanyahu and his government, who are still killing Palestinians in the Gaza Strip and the occupied West Bank on a daily basis, are increasingly being seen as eager to drag the region – and the United States – into an expanded conflict.

But the significant increase of Israeli attacks on Lebanon “will not be without effect in accelerating Iran’s response”, according to Hadi Afghahi, a West Asia analyst and former Iranian charge d’affaires to Lebanon.

He told Al Jazeera that this was especially true after the “fiery” speech delivered by the supreme leader during a meeting with military commanders on Wednesday, when he asserted that Hezbollah had not been brought to its knees despite taking considerable blows. Khamenei promised that “final victory will belong to the resistance front and the Hezbollah front”.

“Iran will not wait so long as to make the enemy insolent and believe that there will be no strike back. After the supreme leader’s speech, I think a strike will take place soon,” Afghahi said.

He said that the most explicit comments about the nature of the Iranian retaliation against Israel so far have been delivered by Major General Mohammad Bagheri, chief of staff of Iranian armed forces, who stated Tehran will respond decisively and independently of the “axis of resistance”.

Afghahi pointed out that Hezbollah has launched a ballistic missile at Tel Aviv for the first time, the Houthis in Yemen successfully landed a hypersonic ballistic missile in central Israel, and the Islamic Resistance in Iraq is ramping up its attacks using new missiles and drones. But Iran would likely wish to further display and also evaluate the effectiveness of its weapons in independent attacks, rather than a joint attack.

“And a potential war will not simply be a war of missiles and drones, it would be a hybrid war,” the former official explained. “I have heard from a military official that we might even be considering going after a number of high-ranking Israeli political or military officials amid the war and our retaliatory operation. The Zionist regime has used assassination as a method since its founding, so if there is an assassination against these war criminals, it would be considered as retaliation and self-defence.”

Afghahi emphasised that the Iranian response “will be within the framework of international law”, meaning no places of worship, schools, markets or other civilian infrastructure will be attacked, making a distinction with Israel’s repeated attacks on non-military targets.

‘Maintaining the initiative’

The election of centrist President Masoud Pezeshkian could mean that Tehran will display more “flexibility and strategic patience” overall, but “there are no disagreements over the nature, legitimacy or certainty of the response” among top Iranian leadership, Afghahi explained.

Pezeshkian struck a moderate tone during his first address to the United Nations General Assembly on Wednesday, including saying Iran wants to hold more talks with the West and other global powers on its nuclear programme and US sanctions.

But he also railed against the “genocide” being perpetrated in Gaza and called for a ceasefire. After returning to Tehran on Thursday, he told reporters that his team spoke with 15 countries about Gaza and Lebanon, and asserted that “the Zionist regime and its supporters are the biggest terrorists” who are killing civilians while claiming to be supporters of human rights and international law.

Iran wishes to reserve a legitimate right to respond to a violation of its sovereignty and territory while remaining mindful of Israel’s goals, according to Sasan Karimi, a professor at the Faculty of World Studies of the University of Tehran.

He told Al Jazeera that Netanyahu is trying to protect himself politically, but Israel has adopted an overall “thousand daggers” policy since it realises it cannot defeat Iran with a single big blow.

“The Islamic Republic has preferred at this stage to consciously maintain the initiative and not lose it even in response to Israeli acts of terror. In this vein, the timing, nature and scale of this reaction will be set in Tehran while maintaining a sense of agency,” Karimi said, adding that Iran will not be forced into an uncalculated response that could prompt more Western backing for Israel, even after the escalating attacks on Lebanon.

The US has brought significant military force into the region, including aircraft carriers, fighter jets and missiles following the assassination of Haniyeh in order to prevent another large-scale direct Iranian attack on Israel like the one last April, when Israel and its Western allies defended against hundreds of Iranian missiles and drones.

The Pentagon said last week that it has detected no change in Iranian force posture that would indicate an imminent attack.

Karimi said Iran would want more predictability while maintaining an element of surprise in its attack – whereas the Islamic Revolutionary Guard Corps’s (IRGC) unprecedented attack on Israel in April was carefully telegraphed.

“The Islamic Republic of Iran does not wish to turn war into its main issue, which is something Israel wants at the moment. I believe Iran’s response will be patient but more real than what may initially come to mind,” he said.