NEW YORK — In cities across Iran, tens of thousands packed the streets to mourn Major-General Qassem Soleimani.

Black-clad women and men beat their chests and clutched photos of him. A black flag went up on the golden dome of Imam Reza shrine in the city of Mashhad, one of the holiest sites of Shiite Islam.

Just a few weeks earlier, the streets were filled with protesters angry with their leaders over the flailing economy and the country’s international isolation.

But at least for now, Iran is united — in anger at the United States.

For years, it has been a divided nation led by aged revolutionaries determined to impose their will on a predominantly young population with no memory of the shah, who was deposed in the 1979 Islamic Revolution, and with a thirst to live in a more normal nation integrated into the world.

Suddenly, with one targeted assassination, the nation rallied behind its leaders.

Young and old. Rich and poor. Hard-liner and reformer. Soleimani, Iran’s most powerful military leader, was almost universally admired and had near cult figure status.

After being killed in Baghdad on Friday in a drone strike ordered by US President Donald Trump, his image is now plastered across Tehran, shrouded in black drapes.

“Without doubt, the people of Iran will take revenge for this horrific criminal act,” tweeted the Iranian president, Mr Hassan Rouhani, a leader who once advocated diplomacy and integration with the West.

In Iraq on Saturday, tens of thousands of pro-Iranian fighters marched through the capital, Baghdad, vowing to exact revenge on the United States at a funeral procession for two revered Iraqi military figures who were also killed in the attack on Soleimani.

And back in Iran, politicians and ordinary people of all stripes voiced support for the vow by the supreme leader, Ayatollah Ali Khamenei, that “severe revenge awaits those criminals” who killed the general.

The assassination appears to have solidified the hard-liners’ grip on power, neutralising at least for the moment those who had called for talks with the West, experts inside and outside of Iran said.

Iran’s relative moderates like Mr Rouhani have been on the defensive since Mr Trump withdrew from the 2015 nuclear deal and imposed an array of sanctions, contributing to Iran’s sharp economic decline.

That reversal bolstered hard-line critics who said it discredited those who had accepted American assurances. Moderates had nurtured fading hopes of renewed talks with Washington — possibly between the two presidents.

Any talk of outreach or liberalisation seems more dangerous than it has in years and is likely to fade from public debate for the time being. The prospect of negotiations with the United States, tweeted Ms Sara Masoumi, a prominent reformist journalist, is now “below zero.”

“At least in the short term, this will create a rally to the flag. Soleimani was personally popular,” said Prof Vali Nasr, a Middle East scholar and former dean of Johns Hopkins University’s School of Advanced International Studies. He predicted “an outpouring of emotion,” both organic and whipped up by the government.

Iran is bestowing honors on Soleimani as if he were a combination of statesman and saint. His body will circulate around shrines in all the holy cities of Shiite Islam from Samarra, Kadhimiya, Karbala and Najaf in Iraq to Mashhad and Qom in Iran.

As his body makes its way to four Iranian cities over the next few days, large crowds are expected to attend and display their solidarity and defiance. This show of unity, however, could be short-lived.

Soleimani’s killing “was the worst thing that could happen to civic movements in Iran and Iraq,” said Mr Amir Rashidi, an Iranian cybersecurity expert based in New York.

“It means more pressure on people who are already being squeezed politically and economically.”

In just a few days, the conflict between the United States and Iran has escalated drastically. A rocket attack on a military base in Iraq killed an American on Dec 27. 

The United States blamed it on an Iran-backed militia and that weekend carried out airstrikes that killed some two dozen militia fighters. Then, last Tuesday (Dec 31), militias swarmed the US embassy compound in Baghdad, breached the outer wall and set fire to some structures.

Soleimani led the Quds Force of Iran’s Revolutionary Guard, which conducts Iran’s foreign military operations. He commanded Iranian forces battling the Islamic State group in Iraq and Syria.

He also headed Iran’s role in arming, training and directing anti-ISIS Shiite militias. The American attack that killed him also killed the powerful leader of Iran-backed militias in Iraq, Abu Mahdi al-Muhandis.

In addition, the general directed Iran’s involvement with forces like the Houthi rebels in Yemen, Hezbollah in Lebanon and others that are in conflict with the United States and its regional allies, Israel and Saudi Arabia. The United States had labeled him a terrorist since 2007 and imposed economic sanctions on him.

But in Iran, the government built up his public image as the person keeping the country safe.

He went from a commander in the shadows to a household name, regularly seen in news videos directing troops in battle, meeting with allied leaders and reciting poetry about martyrdom.

“Qassem SoleimaniSoleimani has been seen as the public face of Iran’s regional policy,” said Dr Sanam Vakil, a senior research fellow and leader of the Iran Forum at Chatham House, an international affairs institute based in London. “Since the fight against ISIS, you’ve seen this surge of support for him.”

Iranians who are usually outspoken in support of human rights have turned to national solidarity and sorrow at his death.

“How soon we forget how close ISIS was to us and who defeated this monster,” actress Bahareh Rahnama posted on her Instagram account. One of Iran’s biggest celebrities, she is well known for her support of women’s rights.

Soleimani was broadly thought of as a conservative, but he took care not to align himself with any political faction in Iran or take sides in domestic disputes, allowing him to be seen as above politics.

“He’s someone who had a depth and breadth of relationships within the Iranian system that allowed him to work with all key players,” said Dr Ariane Tabatabai, an associate political scientist at the RAND Corp focused on the Middle East and Iran. She cited his close working relationship with Iran’s foreign minister, Mr Mohammad Javad Zarif, who is seen as a moderate.

“Every major political actor within Iran, from reformist to hard-liner, is saying this is a great loss,” she said. THE NEW YORK TIMES