By Parisa Hafezi and Jeff Mason
Iran's supreme leader wept as huge crowds of mourners thronged Tehran's streets for the funeral of military commander Qassem Soleimani, killed in a drone attack on the orders of the US government.
As the coffins of General Qassem Soleimani and Iraqi militia leader Abu Mahdi al-Muhandis, who also died in Friday's attack in Baghdad, were passed over the heads of mourners, Soleimani's successor vowed to expel US forces from the region in revenge.
The killing of Soleimani, the architect of Iran's drive to build its influence in the Middle East, has stoked concern around the globe that a broader regional conflict could now erupt.
Trump has listed 52 Iranian targets, including cultural sites, that could be hit if Iran retaliates with attacks on Americans or US assets, although officials sought to play down the president's reference to cultural targets.
General Esmail Ghaani, the new commander of the Quds Force, the elite unit of Iran's Revolutionary Guards charged with overseas operations, promised to "continue martyr Soleimani's cause as firmly as before with the help of God, and in return for his martyrdom we aim to rid the region of America".
"God the Almighty has promised to take martyr Soleimani's revenge," he told state television. "Certainly, actions will be taken."
Other political and military leaders have made similar, unspecific threats. Iran, which lies at the mouth of the key Gulf oil shipping route, has a range of proxy forces in the region through which it could act.
The crowd in Tehran, which state media said numbered in the millions, recalled the masses that gathered in 1989 for the funeral of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini.
Soleimani was a national hero in Iran - even to many who do not consider themselves supporters of Iran's clerical rulers.
Aerial footage showed people packing thoroughfares and side streets and chanting "Death to America!", a welcome show of national unity for Tehran after anti-government protests in November.
Assassination unifies Iraq's factions against US
Iran's demand that US forces quit the region gained traction on Sunday when Iraq's parliament backed the prime minister's recommendation for foreign troops to be ordered out of the country.
Iraq's rival Shi'ite leaders, including ones opposed to Iranian influence, have united since Friday's attack to call for the expulsion of US troops, who number about 5,000, most of them advisers.
Soleimani, widely seen as Iran's second most powerful figure behind Khamenei, built a network of proxy forces to create a crescent of influence stretching from Lebanon through Syria and Iraq to Iran. Allies also include Palestinian and Yemeni groups.
He notably mobilised Shi'ite Muslim militia forces in Iraq that helped to crush Islamic State, the Sunni terror group that had seized control of swathes of Syria and Iraq in 2013-14.
Have you EVER seen such a sea of humanity in your life, @realdonaldtrump?— Javad Zarif (@JZarif) January 6, 2020
Do you still want to listen to the clowns advising you on our region?
And do you still imagine you can break the will of this great nation & its people?
End of malign US presence in West Asia has begun. pic.twitter.com/5WzYM9OBuQ
Washington, however, has accused Soleimani of attacks on US forces and their allies.
Prayers at Soleimani's funeral in Tehran, which was later due to move to his southern home city of Kerman, were led by Khamenei, who wept as he spoke.
His daughter Zeinab Soleimani told mourners the United States would face a "dark day" for her father's death.
Ismail Haniyeh, leader of the Palestinian militant group Hamas, on his first trip to Iran since taking up his role in 2017, said "resistance against American dominance will not be broken".
Adding to tensions, Iran said it was taking another step back from commitments under a 2015 nuclear deal with six powers that Washington withdrew from in 2018.
Britain said Iran's move was "extremely concerning" and Germany said it would still work to save the pact.
After the United States imposed new sanctions on Iran, saying it wanted to halt Iranian oil exports, the main source of government revenues. Iran's economy has been in freefall as the currency has plunged.
Trump's adviser Kellyanne Conway said today Trump was confident he could renegotiate a new nuclear agreement "if Iran wants to start behaving like a normal country".
Trump's 'threat of war crimes'
Tehran has said Washington must return to the existing nuclear pact and lift the crippling sanctions before any talks can take place.
Trump stood by remarks that cultural sites were potential targets, despite criticism from US politicians that this amounted to a threat to commit war crimes.
"They're allowed to kill our people. They're allowed to torture and maim our people. They're allowed to use roadside bombs and blow up our people. And we're not allowed to touch their cultural sites? It doesn't work that way," Trump said.
Democratic critics of the Republican president have said Trump was reckless in authorising the strike. Republicans in the US Congress have generally backed his move.
Trump also threatened sanctions against Iraq and said Baghdad would have to pay Washington for an air base in Iraq if US troops were required to leave.
It was not clear if Washington had advised its allies of its plans before killing Soleimani. Britain, which also has troops in Iraq, said it understood why the United States had acted but called for a de-escalation to avoid war.
Oil prices were up around 1 percent since Friday at around $US69.30 per barrel of Brent crude on concerns about an escalation.
Will tensions affect NZ trade?
The chief executive of BusinessNZ predicts tensions in Iran will do little to affect New Zealand trade, but it could have larger ramifications for the global market.
BusinessNZ chief executive Kirk Hope said a big question was what it would mean for the impending trade deal between the US and China.
"Whatever the various positions in respect of Iran are between China and the US may have some form of implication for them coming to an agreement and ending the trade war," he said.
Hope said rising oil prices and decreasing interest rates could also impact New Zealand.
"Oil will affect us if they increase beyond 20 percent and it depends clearly on the supply lines," he said.
However, he added that it was unlikely to change much in terms of New Zealand exports to Iran, which are already being restricted.
"New Zealand has always had a form of trade with Iran in particular they have imported a lot of our sheep meat, but the challenge has always been getting paid because of the US sanctions that have operated in Iran for a long time, which have then escalated again [in 2018]," he said.