Iran says it will take Donald Trump to The Hague over the US drone strike which killed top general Qassem Soleimani.
Tehran wants to file a war crimes lawsuit at the International Court of Justice after the Quds Force commander was killed in Iraq on January 3, reports Daily Mail.
The US does not accept the court's jurisdiction but the case could become an embarrassment for Washington if judges find in favour of Iran, which they have done in the past.
UN investigator Agnes Callamard - who wrote a damning report into the death of Saudi journalist Jamal Khashoggi last year - has said that Soleimani's killing 'most likely violates international law'.
The case could also help the Iranian regime to turn public anger back against Washington after a wave of domestic fury over the plane crash which killed 176 last week.
Iran's Revolutionary Guards shot down the Ukrainian passenger jet in error last Wednesday and only admitted their mistake after three days of falsehoods.
The Guards have since arrested a person accused of sharing footage of the missile strike.
Iranian judiciary spokesman Gholamhossein Esmaili said the US had committed a 'terrorist act' by eliminating Soleimani, according to Iranian media.
'We intend to file lawsuits in the Islamic Republic, Iraq and The Hague Court [the International Court of Justice],' he said.
Callamard, the UN investigator, said at the time of Soleimani's death that it was 'hard to imagine' how it could be justified under international law.
'The targeted killings of Qasem Soleimani and Abu Mahdi al-Muhandis most likely violate international law [including] human rights law,' she said.
'Lawful justifications for such killings are very narrowly defined and it is hard to imagine how any of these can apply to these killings.'
The court in The Hague has previously found in Iran's favour by ordering the US to ensure that sanctions on Tehran did not affect humanitarian aid.
The US does not accept the ICJ's compulsory jurisdiction.
Today Iran's foreign minister Mohammad Javad Zarif said the drone strike against Soleimani was an 'unprovoked attack', although Washington says the general posed an 'imminent' threat to Americans.
Iran fired back with missile strikes on US bases in Iraq in what Zarif today called an act of 'self-defence'.
Hours later, a plane came down near Tehran in what the regime now admits was an erroneous missile strike.
Iran initially spent three days claiming that the plane had suffered a technical failure and dismissed claims of a shoot-down as 'psychological warfare'.
The regime finally abandoned its pretence on Saturday, sparking a fresh wave of protests against the government.
Dozens of protesters chanted slogans at a Tehran university and a vigil for the crash victims boiled over into demonstrations.
'We lost the lives of [176] people because of tensions created by the United States,' the foreign minister said today, referring to the plane crash.
Zarif said Iranian citizens had an 'expectation that the government should have disclosed information' on the downing of the Boeing 737 last Wednesday.
'In the last few nights, we've had people in the streets of Tehran demonstrating against the fact that they were lied to for a couple of days,' Zarif said.
Speaking on a visit to India, Zarif said the missile strike was an 'unforgivable mistake' amid fury at the regime after dozens of Iranians died in the air disaster.
Several video clips have shown the moment the plane came down, and one Iranian who published footage has reportedly been arrested.
Iran's semi-official Fars news agency reported the arrest of a person accused of sharing footage, but did not say which of the various clips was being investigated.
A journalist who shared one piece of footage last week says the source who provided it is safe, raising fears that the wrong person could have been arrested.
Zarif also blamed 'US arrogance' for fuelling the 'mayhem' in the Middle East which prompted Tehran to shoot down the jet by mistake.
A vigil for the victims in Tehran sparked a diplomatic row when Iran arrested the British ambassador Rob Macaire, who said he had left when the memorial turned into protests.
The UK government yesterday summoned Iran's ambassador in London to voice its anger over the breach of diplomatic protocol.
Zarif went on to praise Iran's military for being 'brave enough to claim responsibility early on.'
He also claimed that he and President Hassan Rouhani only learned that a missile had downed the flight on Friday, challenging claims of a cover-up.
Zarif also said the nuclear deal with Western powers and Russia was not dead, despite Tehran's near-abandonment of the pact.
Iran has said it will no longer abide by any of the nuclear limits under the 2015 deal, which was intended to prevent it from developing a nuclear weapon.
Donald Trump pulled out of the deal last year but European powers say they want to keep it alive.
Around 30 people have been arrested in the protests over the air disaster, according to judiciary spokesman Gholamhossein Esmaili.
In another sign of growing dissent, several artists have cancelled their involvement in the Fajr festival, held each year on the anniversary of the 1979 Islamic Revolution.
Recent protests have been much smaller than nationwide demonstrations against fuel price hikes that turned deadly in November.
But one commentator said the latest rallies showed there was a 'real rift between the people and the authorities'.
'I hope that (police restraint) will continue and that no lives are lost, because this could be a catalyst for more protests,' said Mehdi Rahmanian, director of reformist daily Shargh.
Iran said yesterday that authorities have made several arrests after an 'extensive investigation', without saying how many.
President Hassan Rouhani said Tuesday Iran's judiciary 'must form a special court with a high-ranking judge and dozens of experts... The whole world will be watching.'
'Anyone who should be punished must be punished,' he said.
Ukraine has today demanded access to the Boeing 737's two black boxes, which were recovered from the wreckage.
Iranian officials have said the flight recorders are damaged and say it could take months to extract information from them.
A top Ukraine security official said this week that a senior investigator from Iran was expected to visit Ukraine soon.