'This was an intelligence-based assessment that drove our decision-making process,' Pompeo said.
Iranian military commander Qasem Soleimani was planning "imminent" action which would have threatened hundreds of American citizens, US State Secretary Mike Pompeo said on Friday after Soleimani was killed in US strike in Baghdad.
"Soleimani was actively plotting in the region to take actions, a big action, as he described it, that would have put dozens if not hundreds of American lives at risk," Pompeo told local media.
"We know it was imminent," Pompeo also said of Soleimani's plot, without going into detail about the nature of the planned operation.
He also said that he had spoken with British Foreign Secretary Dominic Raab, German Foreign Minister Heiko Maas and Chinese Politburo member Yang Jiechi about the killing and is thankful that the "allies recognise the continuing aggressive threats posed by the Iranian Quds Force."
"Thankful that our allies recognize the continuing aggressive threats posed by the Iranian Quds Force," he wrote on microblogging site.
"The US remains committed to de-escalation."
Pro-Iranian demonstrators laid siege to the US embassy in Baghdad on Tuesday, angered by US weekend airstrikes that killed two dozen fighters from the hardline Kataeb Hezbollah paramilitary group.
The strikes were in response to a rocket attack last week that killed an American contractor working in Iraq.
The Pentagon said Soleimani had orchestrated attacks on coalition bases in Iraq over the past few months, including on December 27, the day the contractor was killed.
Soleimani "also approved the attacks" on the US embassy in Baghdad, according to the Pentagon.