The American killing of a legendary Iranian general seemed for a moment to sweep away months of violent protests against corruption and misrule, drowning it all in nationalist outrage.
But now the crash of a civilian airliner over Tehran on Wednesday is threatening to dissolve that unity in an agonizing debate over whether the Iranian authorities bear the blame. All 176 people on board were killed, including many young Iranians headed for graduate study in Canada.
The United States, Canada and other Western governments concluded that Iran’s own missile defense systems accidentally shot down the plane, but Tehran continued on Friday to dismiss the crash as a mechanical failure that happened to occur just as Iran was bracing for a potential American airstrike.
Many Iranians said that their anger over the lack of accountability at the highest levels of their government has quickly returned.
“Our lives have no value,” Yalda, a 45-year-old graphic artist in Tehran, said in a telephone interview, asking not to be identified fully for fear of arrest. “They shot down the plane and not only do they not apologize but they are lying about it.”
By late Friday, government officials were considering acknowledging that Iranian defense systems brought down the jet, according to four Iranians familiar with the deliberations. Tehran may argue instead, they said, that faulty equipment onboard the plane had failed to signal properly.
The plane crash is only the latest in a series of deadly episodes for which Iranian critics have blamed their government. Fifty-six people were killed Tuesday in stampede in a narrow side street during a funeral procession for the military leader, Maj. Gen. Qassim Suleimani, in his hometown, Kerman.
As many as 600 others were killed this fall by security forces suppressing antigovernment protests. The demonstrations, which began over a sharp increase in gasoline prices, turned into protests about corruption and self-dealing by the authorities in Tehran. The protesters said Iran’s government had plunged Iran into an economic crisis even before American sanctions began to bite.
But the magnitude and timing of the crash, as well as official dissembling about it, have given it special resonance at a moment when Iranian leaders are rallying the public to endure more hardship in their continuing standoff with Washington.
Heading into next month’s parliamentary elections, the disaster is also almost certain to become a campaign issue.
“This will be a big test for the government, and if there is a sense of blurring evidence or hiding something, that is going to hurt the legitimacy of the current system for sure,” said Aniseh Bassiri Tabrizi, a scholar of Iran at the Royal United Services Institute. “We are talking about a very large number of civilians.”
The government has struggled in vain to contain the embarrassment. After insisting the day after the crash that mechanical failure was to blame, the Iranian authorities abruptly shifted on Friday to pledging complete openness. Officials promised to invite investigators from several nations, including France, the United States and the home country of the airline, Ukraine.
Even while pledging a transparent inquiry, though, government officials were still denying on Friday that Iranian missiles could have played any role. State media outlets said the conclusion of the Western governments was an American lie cooked up to sap Iran’s resolve, and some nationalists on social media argued the same.
“One day the story of the Ukrainian airline crash will be taught in schools for lessons in psychological warfare,” Mohammad Keshvari, the chief executive of an Iranian information technology company, argued on Twitter.
As speculation circulated on Iranian social media late Friday that the government might acknowledge some role in the crash, the groundswell of anger appeared to be growing. The hashtag #cheaplife began surging on Iranian social media soon after the Western assessment of the crash began to emerge.
Some compared the government statements about the crash to false official statements that a barrage of Iranian missiles had killed 80 American troops in Iraq on Wednesday. (Pentagon officials say none died.)
“The Islamic Republic is being modest saying it killed 80 in the harsh revenge operation,” tweeted Dariush Zand, a 27-year-old activist living in Turkey. “In reality they killed 176.”
Some complained about the absence of official mourning for those who died on the plane. Pictures of General Suleimani had sprung up everywhere, memorials for him went on through the night, and mosques erected small shrines in his honor. But there were no public condolences or flags at half-staff to honor those who died in the plane.
“Nobody trusts the government,” said Sara, a 42-year-old translator in Tehran. “Lie on top of lie. They were not transparent about the number of people killed in the protests in November, they were not transparent about what brought the plane down. The only thing they are transparent about is their propaganda for Suleimani.”
Some said they felt indignant that only reports from the West had prompted the inquiries. “If America and Canada hadn’t revealed the truth, Iran would continue to lie,” said Mehdi, a 37-year-old journalist in Tehran. “We can’t process this.”
For many, the crash has an added poignancy because the plane was carrying many of Iran’s best and brightest. A large number of the passengers were graduates of top science and engineering schools headed for fellowships, graduate school or teaching jobs in Canada. Fourteen were graduates of Iran’s elite Sharif University of Technology, a top supplier of M.I.T. and Stanford recruits.
“We see ourselves in them,” said Solmaz Sharif, an Iranian journalist who emigrated to the United States a decade ago. They were “the people who immigrated hoping for a better life and worked hard to create that life and still loved Iran and went back to visit. Only to be killed.”
In the heat of the recent clashes with Washington, though, other Iranians insisted that the United States was as much to blame for bringing down the passenger jet as for killing General Suleimani.
“The possibility of US maliciously jamming the Boeing plan’s system is stronger than the Revolutionary Guards mistakenly targeting a passenger plane,” tweeted Mahziyar Khaki, a cleric from Qom.
Ramin Ghorbani, another Iranian Twitter user, changed his profile to a picture of General Suleimani. “Looks like the Americans are responsible for the plane crash,” Mr. Ghorbani wrote. “It’s a plan to divert public attention from General Suleimani’s martyrdom and find an excuse to impose more sanctions on us.”
Government officials pleaded for a return to the solidarity that followed the killing of General Suleimani. “This was an extremely difficult week for Iranians,” tweeted Gholamhossein Mohamadi, the head of Tehran municipality’s communication department. “The only way out of this crisis is national unity.”
But Amir Ali, a 46-year-old owner of an advertising agency in Tehran, said even families were becoming divided over the blame for the crash.
“Everyone is confused and shocked,” he said. “Unfortunately, there is a lot of disagreement.”