A stampede at the funeral Tuesday for top Iranian military commander Qassem Soleimani killed at least 40 people and injured more than 200 others, Iranian state media reported.
Tens of thousands of people had gathered to honor Soleimani in his hometown of Kerman before his burial, following similar ceremonies this week in Tehran, Qom and Ahvaz. The state media reports said the burial was postponed following the stampede.
Many of the mourners screamed for retaliation against the United States for the killing of Soleimani, taken out in a drone strike last week at the Baghdad airport on orders of U.S. President Donald Trump. "No compromise, no submission, revenge!" they shouted.
Soleimani's killing has sparked fears of a wider conflict as the United States and Iran threatened strong responses to each other's actions.
Iranian Foreign Minister Mohammad Javad Zarif contended in a CNN interview that the U.S. killing of Soleimani, commander of the Revolutionary Guard's Quds Force, constituted "state terrorism."
“This is an act of aggression against Iran, and it amounts to an armed attack against Iran, and we will respond," Zarif said. "But we will respond proportionately - not disproportionately ... we are not lawless like President Trump.”
U.S. officials have blamed Soleimani for the killings of American troops in Iraq by Iranian-backed forces and accused him of plotting "imminent" new attacks against U.S. personnel in the region, while not publicly disclosing the nature of the threat.
With tensions between the United States and Iran raised, the U.S. has denied Iranian Foreign Minister Mohammad Javad Zarif a visa to travel to New York for upcoming United Nations meetings.
Following the airstrike, Iran also announced it was further cutting its compliance with the 2015 agreement that restrained its nuclear program. That prompted U.S. President Donald Trump, who withdrew from the deal and applied new sanctions against Iran, to tweet Monday, "IRAN WILL NEVER HAVE A NUCLEAR WEAPON!"
Trump also vowed late Sunday that the U.S. will strike "very hard and very fast" at as many as 52 Iranian targets if Iran attacks U.S. personnel or assets. The number 52 represents the number of Americans Tehran took hostage in 1979 for 444 days.
"They're allowed to kill our people," Trump told reporters aboard Air Force One. "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."
Iranian President Hassan Rouhani rebuffed Trump's threat on Monday, tweeting: "Those who refer to the number 52 should also remember the number 290. #IR655. Never threaten the Iranian nation."
It was a reference to the U.S. mistakenly shooting down an Iranian passenger jet flying over the Persian Gulf in 1988, killing all 290 people aboard the aircraft. Then-U.S. President Ronald Reagan expressed deep regret over the incident and the U.S. paid nearly $62 million in reparations to the victims' families.
As the threats and counter-threats ricocheted between Tehran and Washington, NATO chief Jens Stoltenberg urged Iran to avoid "further violence and provocations." At an emergency session of NATO's ruling council in Brussels, U.S. officials briefed allies about the drone strike that killed Soleimani.
Stoltenberg said it was a "U.S. decision" to launch the attack, but added that the other 28 NATO countries had longstanding concerns about aggressive Iranian military actions in the Middle East.
In another development, U.S. Secretary of State Mike Pompeo met Saudi Deputy Defense Minister Khalid bin Salman Al Saud in Washington. The State Department said Pompeo thanked Al Saud for Riyadh's "continued support" and for "working with the U.S. to counter the threat posed by the Iranian regime."
Speaking to VOA Persian, London-based Iranian dissident and political analyst Alireza Nourizadeh said the demise of Soleimani is welcome news to several of Iran's neighbors.
"Saudi Arabia, Kuwait, Bahrain and Lebanon -- they were targets of Soleimani and endured his attacks," Nourizadeh said.
In another VOA Persian interview, former U.S. ambassador to the UAE Barbara Leaf said majority-Sunni Gulf nations Saudi Arabia and the UAE, who long have accused predominantly-Shi'ite Iran of seeking regional hegemony, both have been "muted" in their public responses to the U.S. killing of Soleimani.
"The theme of their comments essentially is, it is time for de-escalation and a political approach to resolving these issues," said Leaf, an analyst at the Washington Institute for Near East Policy. "It is safe to say that all Gulf countries as well as Iraqis are extremely anxious about the prospect of an escalation to actual clashes between the U.S. and Iran."
The White House said it will brief the entire 100-member Senate about the drone attack on Wednesday. While Republicans have generally supported Trump's action to take out Soleimani, opposition Democrats have called for publication of U.S. intelligence used by his aides to justify the strike.
House Speaker Nancy Pelosi said in a Sunday letter to her Democratic colleagues that the House will vote this week on a war powers resolution "to limit the President's military actions regarding Iran."
"It reasserts Congress's long-established oversight responsibilities by mandating that if no further Congressional action is taken, the Administration's military hostilities with regard to Iran cease within 30 days," Pelosi wrote.
She called last week's airstrike "provocative and disproportionate," and said it endangered U.S. troops while escalating tensions with Iran.
Sen. Lindsey Graham, one of Trump's Republican allies, said the president "did the right thing" and that his national security team is "doing a great job helping President Trump navigate Iranian provocations."
VOA Persian's Katherine Ahn and Afshar Sigarchi contributed to this report.