US has targeted 52 Iranian sites - Trump

President Donald Trump says United States has targeted 52 Iranian sites that it would strike if Iran attacks any Americans or any US assets in response to a US drone strike that killed Iranian military commander Qassem Soleimani in Iraq.

Showing no signs of seeking to reduce tensions raised by the strike on Friday that he had ordered, Trump issued a stern threat to Iran on Twitter.

Trump wrote that Iran "is talking very boldly about targeting certain USA assets" in response to Soleimani's death. Trump said the United States has "targeted 52 Iranian sites" and that some were "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!" Trump said, adding that the 52 targets represented the 52 Americans who were held hostage in Iran after being seized at the US embassy in Tehran in 1979.

Soleimani was killed in the US strike on his convoy at Baghdad airport. Iranian-backed Iraqi militia leader Abu Mahdi al-Muhandis was also killed in a US strike that has raised the specter of wider conflict in the Middle East.

The Republican president's tweets were issued during his holiday stay in Florida. A rising number of Democrats have said Trump's action is bringing the United States to the brink of war.

On Saturday, tens of thousands of people marched in Iraq to mourn Soleimani and the Iraqi militia leader. On Saturday evening, a rocket fell inside Baghdad's heavily fortified Green Zone near the US Embassy, another hit the nearby Jadriya neighborhood and two more rockets were fired at the Balad air base north of the city, but no one was killed, the Iraqi military said in a statement.