The Army General Staff stressed that the tragic mistake was made amid the flare-up of tensions with Washington. The nation's air defenses were placed on alert and ready to "respond to possible threats of the highest level," after US President Donald Trump warned that the Pentagon would strike targets on Iranian soil if US citizens or assets were attacked by Iran.

On Wednesday, the Iranian Army fired a volley of ballistic missiles at two bases in Iraq that house American troops. It was a retaliation in response to a US drone strike, which killed top Iranian military chief Qassem Soleimani at Baghdad's airport.

For several hours after the missile attacks, the army was detecting increased activity of US warplanes around the country and received alerts of possible airstrikes on "strategic sites" across Iran, the General Staff said.