"The administration has sent Congress a legally mandated report outlining its legal and policy justifications for the strike that killed Iranian General Qassem Soleimani. This official report directly contradicts the President’s false assertion that he attacked Iran to prevent an imminent attack against United States personnel and embassies," Engel said.
The January 3 killing of Soleimani in a US drone strike near Baghdad’s international airport prompted a spate of confusing explanations.
The US Defence Department blamed Soleimani for a rocket attack days earlier that killed an American military contractor, adding that the Iranian commander was developing plans to kill US diplomats and soldiers.
Trump later said Soleimani was planning an "imminent" strike on Americans - language echoed by Secretary of State Mike Pompeo and Chairman of the Joint Chiefs of Staff Gen. Mark Milley.
But on Friday, Engel said, "this report makes no mention of any imminent threat and shows that the justification the President offered to the American people was false, plain and simple."
Analysts cited the killing of Soleimani as a key reason for the defection of eight Republican senators who joined Democrats in passing a bill Thursday that would require Trump to get congressional authorization before initiating hostilities against Iran. Trump is expected to veto the measure.