U.S. officials, speaking on the condition of anonymity, told the Associated Press on Saturday that the U.S. military launched cyber-attacks on Iran after the downing of an unmanned U.S. surveillance drone in Iranian airspace on Thursday. Two officials said the cyber-attacks were approved by President Trump; a third official outlined the scope of the attacks.

According to the officials, the cyber-attacks – a contingency plan developed over weeks amid escalating tensions – disabled Iranian computer systems that control its missile and rocket launchers. The attacks specifically targeted Iran’s Islamic Revolutionary Guard Corps(IRGC) computer system. Earlier in the year, the U.S. designated the IRGC as a terrorist organization, a first for a foreign government’s military.

The Associated Press reported one official saying the cyber-attacks were provided as an option after Iranian forces blew up two oil tankers earlier this month. The only “evidence” the U.S. military provided to make that claim was a grainy black and white video of a boat alongside one of the tankers, Tehran has denied the accusation that they attacked the tankers.

No Iranian officials have yet responded to the claims of this cyber-attack, Iran’s Fars news agency said on Sunday. The news agency said it was, “still not clear whether the attacks were effective or not,” and suggested the U.S. media reports were a “bluff meant to affect public opinion and regain lost reputation for the White House” following the downing of its drone.

In 2010 Iran’s nuclear facilities were infected with the so-called stuxnet virus, which is believed to have been a joint U.S.-Israeli creation. Since that cyber-attack Iran has disconnected much of its infrastructure from the internet.

These cyber-attacks are the latest in U.S. aggression against Iran. On Friday President Trump said he restrained from launching an aerial strike on the country but has promised more sanctions.

Dave DeCamp is a freelance journalist based in Brooklyn NY, focusing on US Foreign policy and wars. He is on Twitter at @decampdave.