The assassination of Qassem Soleimani marks the most significant escalation in tensions between the US and Iran in recent years.
The friction is rooted in the 2018 US decision to pull out of a nuclear deal signed in 2015 between Iran and world powers.
The landmark accord is likely to further unravel as Tehran is expected to announce as early as Sunday that it will take another step away from it in the wake of Washington’s withdrawal and reimposition of punishing sanctions.
Following Soleimani’s assassination, Iran’s Supreme Leader Ayatollah Ali Khamenei warned of “harsh revenge” as he called for three days of national mourning while Iranian President Hassan Rouhani said Tehran’s response to the killing would be long and drawn out.
Though it is unclear how or when Iran may respond, any retaliation is likely to come after the mourning period ends.
Luciano Zaccara, research coordinator in Gulf politics at Qatar University told Al Jazeera he believes Iran will not leave the death of Soleimani “unpunished” as he is a popular political figure in Iran.
“The leader and everybody inside Iran already promised that his death will be avenged; it would be very difficult to believe that nothing is going to happen,” Zaccara said.
“Iran has been bragging about their capacity to mobilise other groups outside Iran – Syria, Lebanon, Yemen. Having in mind the attack was conducted inside Iraq, [I assume] that the main target would be American interests in areas where there are American and Iranian troops like Syria or Lebanon or Iraq.”
US President Donald Trump on Saturday threatened to hit 52 Iranian sites “very fast and very hard” if Iran retaliated and attacked US citizens or assets.
Meanwhile, the US has dispatched another 3,000 troops to Kuwait, the latest in a series of deployments in the region in recent months.
In Iraq, where three days of mourning have also been declared, security forces were on high alert, according to Al Jazeera’s Osama Bin Javaid.
Reporting from Baghdad, Bin Javaid said the burial of al-Muhandis would take place in the southern city of Najaf.
Meanwhile, tens of thousands of Iraqis marched on Saturday in several cities to mourn al-Muhandis and Soleimani.
In the evening, a rocket fell inside Baghdad’s heavily-fortified Green Zone near the US embassy, another hit the nearby Jadriya neighbourhood and two more were fired at the Balad airbase north of the capital, but no one was killed, the Iraqi military said in a statement.
There was no immediate claim of responsibility.