The US President Donald Trump claims he called off military strikes against Iran just 10 minutes before they were due to launch.
Planes were in the air and ships in position to strike when the order came to stand down.
The action was initially ordered after Iran shot down a US surveillance drone.
Donald Trump says the US was "cocked and loaded" to retaliate.
The President claims the decision was made after he was told by a US general that 150 people would be killed if the action went ahead.
He says three sites were chosen, but he felt the action would not have been proportionate to the shooting down of an unmanned drone by Iran.