Iran's supreme leader says his country is at war with Israel after Israel launched its biggest ever attack on the country, killing nearly 80 people, including top officials and nuclear scientists.
Iran responded to Israel's attacks, which Israeli Prime Minister Benjamin Netanyahu says will continue for "as many days as it takes", by launching missiles at Israel that killed one person and injured dozens but were mostly intercepted.
Both countries have continued launching strikes. Iranian state TV reported on Saturday that around 60 people, including 20 children, had been killed in an attack on a housing complex in the capital of Tehran.
Two people, meanwhile, were killed in Israel by a missile on Saturday.
The two Middle East powers traded fire at each other last year, as part of an escalation of the war between Israel and the Iran-backed Hamas militants in Gaza.
The renewed conflict is likely to be longer and more deadly, some experts say.
Dr Jessica Genauer, senior lecturer in international relations at Flinders University, told SBS News that as long as Israel continues to strike inside Iran, Iran will continue to trade tit-for-tat strikes.
"The question is how long will these strikes go on for and how much will they escalate?" she said.
Why did Israel attack Iran now?
Netanyahu has long claimed Iran is building nuclear weapons and said Israel attacked Iran in an attempt to destroy nuclear facilities behind what he said would be an "existential threat to Israel".
The United Nations nuclear watchdog concluded this week that Iran was in violation of its obligations under the global non-proliferation treaty, the first time the body has made such a claim against Iran in almost 20 years.
Israeli authorities said dozens were injured in Iran's retaliatory strikes on Jerusalem and Tel Aviv. Israel and Iran are essentially at war, and the conflict could continue for some time, experts say. Source: Getty / picture alliance/dpa
Genauer said talks held between the US and Iran, which US President Donald Trump had pitched as an opportunity to make a big deal with Iran, possibly lifting sanctions on the country and allowing it to continue with nuclear enrichment, also influenced the timing of this attack.
"I think that the fact that the United States has been engaging in direct talks with Iran was not a popular move with the current Israeli government.
"Israelis were concerned that a rapport between the US and Iran would not be in their interests because they would rather see Iran excluded from the international arena than included and brought in from the cold."
Genauer said Israel likely viewed Iran as militarily weak at the moment and sought to further weaken it.
Footage from central Tel Aviv showed fire and smoke rising from a condo tower. Source: AP / Tomer Neuberg
"We're seeing an Iran that's severely degraded is showing that it doesn't have the military capability or military might that it would like to have.
"I think the final reason for the timing that we're seeing now is Benjamin Netanyahu himself, the Israeli prime minister, is very aware that he faces a lot of unpopularity at home in the domestic Israeli context."
What is the role of the US in this conflict?
Trump said Israel fully informed him of its raids ahead of time, but insisted the United States was not involved.
Israel launched dozens of strikes on Iranian cities and nuclear facilities, which Iran has since responded to. Source: AAP / Abedin Taherkenareh
"Israel is very much aware that its own military capabilities have certain limits and cannot entirely destroy Iran's nuclear program."
Israel has indicated that one of its primary targets is Iran's Fordo uranium enrichment facility, which is underground and heavily fortified.
"Israel can't destroy that, but they can damage some of the facilities, and they can provoke a response that would bring the United States into the conflict," Akbarzadeh said.
"And with the US in the conflict, there is a good chance of some major changes in Iran."
Iranian state media reported on Saturday that Iran had warned the US, UK and France that their bases and ships in the region will be targeted if they help stop its strikes on Israel.
Akbarzadeh said the US would be hesitant to enter the conflict, but there is every chance they would, as even the unpredictability of the Trump administration hasn't changed the US' commitment to defend its ally Israel.
Genauer said Trump would be reluctant to involve America in the conflict and wouldn't openly support any escalations between Iran and Israel.
Israel says it has launched strikes against Iran's capital city Tehran. Source: AAP / Vahid Salemi/AP
The US has military bases across Bahrain, Qatar, Iraq and Syria.
What could happen next?
Both sides have said they will continue to strike each other.
Akbarzadeh said that "It's very likely that Iran will continue launching missiles at Israel, and at the moment that's effectively all Iran can do. There are no other options open to Iran."
He said there is a chance that Iran's allies in Shi'ite militias in Iraq could get involved and attack Israel or US assets in Iraq, but that Iran's other allies aren't going to be able to escalate.
Akbarzadeh said there will be many voices in Iran arguing that it should pursue the development of a nuclear bomb, to act in part as a deterrent to Israel attacking it.
Genauer said it's unclear whether Israel has a plan to escalate the conflict in the short term and that its right-wing government could keep attacking Iran until it topples the regime.
In a video address shortly after Israeli fighter jets began striking Iranian nuclear facilities and air defence systems, Netanyahu appealed to the Iranian people directly to rise up and said liberation is near.
"If regime change in Iran is actually the end goal of the current Israeli government, then I would say we are looking at escalation over the medium to long-term or continuation of this current phase of direct conflict in the medium to long-term over the coming months," Genauer said.
— With additional reporting by Reuters.
