The assassination of an Iranian nuclear scientist sparked deep fury in Tehran on Thursday against prime suspect Israel and against the United States, which said it had nothing to do with the murder.
Some hardline newspapers even called for retaliatory action, with one, Keyhan, saying in an editorial that "assassinations of Israeli officials and military are achievable."
The Iranian government's reaction was just as angry, though more measured.
In a letter demanding a strong condemnation from the UN Security Council, it said it had evidence unnamed "foreign quarters" were behind the killing of scientist Mostafa Ahmadi Roshan on Wednesday.
The 32-year-old deputy director of Iran's Natanz uranium enrichment facility died when two riders on a motorbike rode by his car trapped in Tehran's rush-hour traffic and slapped onto it a magnetic bomb that directed a deadly blast inside the vehicle.
The blast also killed Ahmadi Roshan's driver/bodyguard and wounded a third occupant of the Peugeot 405.
The attack was similar to four others that have occurred in Tehran in the past two years. Three scientists, at least two of whom also worked on Iran's controversial nuclear programme, died, while another -- who now heads the country's atomic energy organisation -- escaped just in time.
The latest attack dominated Iran's media on Thursday.
Many outlets criticised what they said was the silence of the West over the killings. More conservative titles urged tit-for-tat covert action against Israel.
"The only way to finish with the enemy's futile actions is retaliation for the assassination of Iran's scientist," the Resalat newspaper said on its front page.
"It is legal under international law to retaliate for the killing of the nuclear scientist," the Keyhan daily said. "The Islamic republic has gathered much experience in 32 years, thus assassinations of Israeli officials and military members are achievable," it added.
The Qods daily's headline read: "Western revenge after Iran announces 20 per cent enrichment."
That referred to Iran's activation of a second uranium enrichment plant, in a fortified mountain bunker in Fordo southwest of Tehran, that was confirmed by the International Atomic Energy Agency on Monday.
The Fars news agency reported that protests over the scientist's killing were to be held on Thursday in front of the French, German and British embassies.
The British embassy has been closed since demonstrators angry at Western sanctions ransacked it at the end of November 2011. The United States and Israel do not have diplomatic ties with Iran. The French embassy is operating on reduced staff.
On Wednesday, Vice President Mohammad Reza Rahimi, the foreign ministry, lawmakers and other officials said Israel and the United States were behind the car-bomb attack.
Israeli officials have largely remained silent, although military spokesman Brigadier General Yoav Mordechai said on his official Facebook page that, while he was unaware who carried out the killing, "I am definitely not shedding a tear."
Israeli media highlighted comments by Israel's military chief of staff, Lieutenant General Benny Gantz, saying the day before the attack that 2012 would be a critical year for Iran, in part because of "things which happen to them (the Iranians) in an unnatural way."
US Secretary of State Hillary Clinton on Wednesday "categorically" denied any US involvement in the bombing.
Iran's powerful Revolutionary Guards, however, were adamant that "the terrorist actions against our nuclear scientists and experts is a US-Zionist plot."
The Revolutionary Guards have previously warned they could strike at enemy targets far beyond Iran's borders should their country be threatened.
Russian Security Council secretary Nikolai Patrushev warned in an interview published by the daily Kommersant on Thursday that military escalation over Iran was likely and that "Israel is pushing the Americans towards it."
"There is a real danger of a US military strike on Iran," he said.
US-Iran tensions are already fraught following an Iranian court's death sentence this week on an American-Iranian former Marine it found guilty of spying for the CIA, and Iran's capture last month of what it said was a CIA drone.
The Revolutionary Guards have announced fresh navy manoeuvres in the strategic Strait of Hormuz in the Gulf within the next few weeks, to underline Iran's threat to close the narrow channel -- a chokepoint for a fifth of the world's oil -- if an attack or heavy sanctions are imposed.
The United States has responded by warning closing the strait would be a "red line" that Iran should not cross. It has sent a second aircraft carrier to waters just outside the Gulf, and a third was on its way.
At the same time, the United States and other Western powers are ratcheting up sanctions on Iran to halt Tehran's nuclear programme they believe masks a drive to research development of nuclear weapons.
Iran denies that its programme is anything but peaceful.