A US strike killed Iran Quds Force chief Qassem Soleimani, the Pentagon said, adding that Soleimani was actively developing plans to attack Americans in Iraq and the Middle East.

"At the direction of the president, the US military has taken decisive defensive action to protect US personnel abroad by killing Qasem Soleimani," a Pentagon statement said.

"This strike was aimed at deterring future Iranian attack plans," it said, adding that the US would continue to take necessary action to protect Americans and interests around the world.

The Pentagon statement said that Soleimani had "orchestrated" attacks on coalition bases in Iraq over the past few months and approved the "attacks" on the US embassy in Baghdad earlier this week.

US officials, speaking on the condition of anonymity, said Soleimani had been killed in a drone strike in Baghdad.

One US official said Iraqi militia commander Abu Mahdi al-Muhandis was also believed to have been killed in the strike, though he was not the primary target.

The official said it was aware of the possibility of an Iranian response and US military officials were ready to defend themselves. 

The official did not rule out additional US troops or military assets going to the region. — Reuters