A forthcoming documentary film, as well as interviews with military and intelligence officials, revealed that the US had planned an extensive cyber attack on Iran’s civil and military infrastructure in case diplomatic attempts to curtail its nuclear programs failed.

Nitro Zeus, the code name for the plan, was designed to disarm Iran’s air defences, communication system and crucial parts of its power grid, the New York Times reported. The plan was cast aside after a nuclear deal was successfully struck between Iran and six other nations last summer.

Pentagon devised the plan to assure US President Barack Obama that America has an alternative other than war if Iran went against it or other regional allies. The plan cost tens of millions of dollars and involved thousands of US military and intelligence personnel, along with installing electronic devices on Iran’s computer network.

The documentary called Zero Days and directed by Alex Gibney will be premiered at the Berlin film festival on Wednesday, the Buzzfeed reported. The film will show that the “Stuxnet” worm, developed by the US and Israel and dismantled one in 5 centrifuges of the nuclear program, was only a small part of a much bigger offensive against the nation

The film will also claim that the US hackers could successfully drill through Iran’s critical infrastructure, working from Remote Operations Centre in Maryland. They were ready to launch an offensive alongside a military operation.

There was a sense of urgency in developing contingency plans for any kind of conflict with Iran, as the White House was aware that Israel is seeking to attack Iran’s nuclear facilities and that the US will be pulled into the hostilities that would erupt. The US intelligence agencies thus developed a cyber attack plan that could destabilise Iran’s Fordo nuclear enrichment plant. Fordo was the most difficult target in Iran, as it was built deep inside a mountain, near the city of Qum.