Donald Trump has claimed plots to attack four US embassies including its consulate in Baghdad prompted his order to kill Qasem Soleimani.
The US president previously said the slain Iranian general was planning to "blow up" an embassy yesterday.
He has consistently said that the military leader posed an "imminent threat" but had not expanded on its scale.
Pressed on this, he told Fox: “I can reveal that I believe it probably would’ve been four embassies.”
President Trump also said he thought the embassy in Baghdad was likely a target.
He added: “We had specific information on an imminent threat and that threat stream included attacks on US embassies. Period. Full stop."
Meanwhile, it has also emerged the US military tried, but failed, to take out another senior Iranian commander on the same day of the killing of Soleimani.
US officials told the Associated Press a military airstrike targeted Abdul Reza Shahla’i, a high-ranking commander in Iran’s Islamic Republican Guard Corps but the mission was not successful.
The Pentagon declined to discuss the highly-classified operation.
President Trump first revealed details of the supposed embassy attack plans yesterday.
He told reporters: "We caught a total monster and we took him out and that should have happened a long time ago.
"We did it because they were looking to blow up our embassy.
"We also did it for other reasons that were very obvious.
"Somebody died, one of our military people died, people were badly wounded just a week before."
His comments come amid rising tensions in the middle east, as the US and Iran clash following the death of Soleimani.
The Iranian military leader was killed in a US-ordered strike over the weekend, which later prompted Iran to target and Iraqi base which homes American and British soldiers.
The US leader said nobody was injured in the retaliatory strike.
The Trump administration has imposed new sanctions on Iran following this week's missile strikes on airbases housing US troops in Iraq.
Secretary of State Mike Pompeo and Treasury Secretary Steven Mnuchin the new sanctions will target eight senior Iranian officials, as well as companies in the steel and other sectors.
Mr Mnuchin said President Trump will issue an executive order imposing sanctions on anyone involved in the Iranian textile, construction, manufacturing or mining sectors.
The administration already reinstated all the US sanctions that were eased under the 2015 nuclear deal.
It also comes as Iran was accused of having shot down a Ukrainian airliner, in a crash which killed 176 people.
Iran denies this though Western nations have suggested intelligence points to a missile having been fired at it - though add that it could have been shot unintentionally.
