Secretary of State Mike Pompeo insisted that despite the lack of specifics, the attacks were really, really imminent.
Iran fired a barrage of missiles in the name of Qassem Soleimani, a top military leader assassinated by the United States.
Boris Johnson's spokesperson, however, insists special relationship remains strong and defends US's right to "self defence".
Explained: How the president's tweet threatens to break four laws.
Iran is vowing retaliation, but it's unclear what form that might take and what its consequences might be.
Richard Ratcliffe said Qassem Soleimani's assassination had "poured cold water" on the case of his wife, jailed in Iran in 2016.
The posts from 2011 and 2012 have resurfaced following the US airstrike that killed Iran’s top general Qassem Soleimani.