Some leading legal and human rights experts say the United States-Israeli strikes on Iran breach international law, with one saying the Australian government risks "trashing" the principles it claims to support by refusing to publicly weigh in on the issue.
As the US military initiated a series of strikes against targets in Iran on Saturday, Israeli defence minister Israel Katz said his military had "launched a pre-emptive strike against Iran to remove threats against the State of Israel".
The US and Israel, both nuclear-armed powers, have long warned against Iran's nuclear program and its support for militant group Hezbollah as a threat to global peace.
Under international law, the use of military force is justified under self-defence if a country is under attack, or if the United Nations Security Council has authorised it.
Ben Saul, Challis Chair of International Law at the Sydney Law School, said the US and Israeli actions breached the fundamental ban on the use of aggressive force under the United Nations Charter and international law.
"This is the most basic rule of international order since 1945, which is being rapidly eroded by actions like this," he told SBS News.
"This is aggression by Israel against Iran. There's no conceivable argument under international law that this is self-defence."
The US and Israel have argued their attacks on Iran are a preventative move to stop the country from acquiring a nuclear weapon and to combat its support for terrorism through Hezbollah and other proxy groups.
Saul, who is also the United Nations Special Rapporteur on Human Rights and Counter-terrorism, said none of these justifications amounted to an armed attack under international law, a legal prerequisite to justify the use of force as an act of self-defence.
"This case does not fall anywhere close to (the argument of) self-defence against an imminent attack," he said.
"I mean, Iran has not yet enriched uranium to the point of building any kind of nuclear device. Experts are all on the same page on that Iran does not have a nuclear weapon."
Don Rothwell, a professor of international law at the Australian National University, also does not believe the US-Israeli attacks were in accordance with international law.
"There's no evidence of an armed attack, there's no evidence of Iran preparing to attack Israel or the United States, and there's no evidence that Iran had nuclear weapons capable of launching such an attack," he said.
Rothwell also highlighted that the UN Security Council had not passed a resolution on an attack on Iran.
"So on that basis, there is no legitimate ground to seek to rely upon the use of force as the United States and Israel seem to have [done] in this instance."
Emily Crawford, a professor of international law at the University of Sydney, said the actions were "not even close" to being compliant with international law.
"Every colleague I've been speaking to, every bit of research that I've been seeing says that there was no evidence to suggest that Iran was going to strike the US in any way such that it would justify the US striking them," she said.
Crawford said it also did not comply with American rules either.
"US law very, very clearly reserves war powers, the right to go to war, to being something that's a congressional vote. And [US President Donald] Trump has completely bypassed Congress here."
'Australia has hitched its wagon to the United States'
Australia has said it supported the US "acting to prevent Iran from obtaining a nuclear weapon and to prevent Iran continuing to threaten international peace and security".
When asked on Sunday by reporters whether the actions were legal, Prime Minister Anthony Albanese declined to offer an assessment.
"Those judgements and statements (are) for the United States and for those involved directly in the attack," he said.
Other countries, however, were far more willing to pass judgement on the attacks' degree of compliance with international law.
Switzerland said it was "deeply alarmed" by the US-Israeli attacks and urged parties to respect international law, also saying it would be open to host diplomatic talks.
Norway's foreign minister said Israel's strikes on Iran broke international law and called for a diplomatic solution to the crisis.
"The attack is described by Israel as a pre-emptive strike, but it is not in accordance with international law. A pre-emptive attack would require the existence of an imminent threat," Espen Barth Eide said in an email sent to Agence France-Presse by his office.
Saul said the Australian government's rhetoric was "deeply disappointing" given that, based on his understanding of governmental processes, it would have already received advice regarding the strikes' degree of accordance with international law.
"To be silent on this, I think, is extremely problematic," Saul said.
"Australia says it supports international law, supports the rules-based international order, is trying to get on the Security Council in an upcoming term, and yet, is in the business of trashing the United Nations Charter and international law.
"Canada and Australia now have backed the United States in this illegal aggression. And I think that's extremely damaging if you have the countries who are supposed to stand up for international law being the ones who are now destroying it."
Saul said these responses set a "dangerous" precedent of a "pattern of a New World Order".
"Trump ... doesn't feel bound by international law. He's only bound by his own morality and whatever strategic objectives the United States has."
'International law does not support regime change'
The US said the campaign was aimed at Iranian missiles and annihilating its navy, following repeated US-Israeli warnings that they would strike Iran again if it pressed ahead with its nuclear and ballistic missile programs.
The US struck Iranian nuclear facilities last year, insisting it had set Iran's nuclear program back decades.
Crawford questioned the logic of the recent strikes if last year's attack was as damaging as the US claimed.
"It does leave you to kind of wonder, 'well, if you'd set it back decades, why are you doing it again?' So I think the 'Iran is about to get the bomb' [argument] is quite a furphy."
"I know a number of people who actually work in international nuclear security, and they're quite open about saying Iran was nowhere near this and was never going to be, but this is all just a cover for regime change.
"International law does not support regime change as grounds for intervention."
Trump said "justice" had been served by the killing of Iran's supreme leader Ali Khamenei in the recent strikes.
"This is not only Justice for the people of Iran, but for all Great Americans, and those people from many Countries throughout the World, that have been killed or mutilated by Khamenei and his gang of bloodthirsty THUGS," he wrote on his social media channel.
Rothwell said that, if Khamenei had committed international crimes, he should have been subject to arrest by the International Criminal Court or by an equivalent body.
"There's no evidence at all that Khamenei is subject to an international arrest warrant. To my knowledge, he's not even subject to any arrest warrants issued by the United States or by Israel. And in any event, even if he was, this would be an example of what's called an extrajudicial killing."
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