Video report by ITV News Correspondent Neil Connery
Donald Trump has threatened to strike 52 Iranian sites "very fast and very hard" if Tehran launches an attack on American forces or assets.
The US president warned Iran off any possible strikes after the Islamic Republic vowed to take revenge on the US following the killing of General Qassem Soleimani, the head of Iran’s elite Quds Force.
Writing on Twitter, he wrote: "Let this serve as a WARNING that if Iran strikes any Americans, or American assets, we have targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level & important to Iran & the Iranian culture, and those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD.
"The USA wants no more threats!"
The number of locations Trump has threatened to attack, 52, is the same as the number of American citizens which were seized by Iran in the US embassy in Tehran and held for more than a year between 1979 to 1981.
Despite diplomats saying they do not want an escalation between the US and Iran, there are fears tensions between the two countries could boil over.
Trump's warning to Iran comes after several rockets exploded near the US embassy in Baghdad, and hours after thousands took to the streets for the funeral of Soleimani.
At least one rocket landed inside the Green Zone in the Iraqi city, which houses government offices and foreign embassies, including the US embassy.
No-one was injured by a Katyusha rocket that fell inside the square less than a mile from the embassy, according to an Iraqi security official.
The security official said another rocket in Baghdad landed about 500 metres from As-Salam palace, where the Iraqi president Barham Salih normally stays in Jadriya, a neighbourhood adjacent to the Green Zone.
Another security official said three rockets fell outside an air base north of Baghdad, where American contractors are normally present.
The rockets landed outside the base in a farm area and there were no reports of damage, according to the official.
It is unclear who fired the rockets, and how many troops are at the airbase, but there are no reports of injuries at either site.
In thinly-veiled threat, one of the Iran-backed militia, Asaib Ahl al-Haq, or League of the Righteous, called on Iraqi security forces to stay at least 1,000 meters away from US bases starting Sunday night.
Iran has vowed harsh retaliation, raising fears of an all-out war – though US President Donald Trump has said he ordered the strike to prevent a conflict as his administration believes Soleimani was plotting a series of attacks that endangered American troops and officials.
The mourners carried Iraqi flags and the flags of Iran-backed militias that are fiercely loyal to Soleimani.