In the early days of President Obama’s administration, thousands of American military and intelligence officers worked to develop a plan that could feasibly take down critical infrastructure in Iran, according to a new documentary called Zero Days, which premieres tomorrow. The plan was codenamed Nitro Zeus, and if it had ever been deployed, it would have taken down parts of Iran’s civilian infrastructure, including its power grid, phone lines, and air defenses. The plan cost tens of millions of dollars to design and involved the placement of electronic implants in Iranian computer networks, in case it were ever decided to be implemented.

The New York Times and BuzzFeed News independently investigated the documentary’s claims. The reports claim Nitro Zeus was created as a contingency plan if the US / Iran nuclear negotiations never came to fruition; the US worried Israel would attack Iran’s nuclear arsenal and drag the US into a conflict. The plan was intended to render a conventional conflict unnecessary, or at least minimize it.

The US also developed a narrower plan that would have taken down Iran's Fordo nuclear enrichment site, the Times reports. The nuclear facility was apparently high on the priority list for the US and Israel after the Stuxnet virus destroyed 1,000 centrifuges and halted activities at the separate Natanz nuclear facility. Fordo would have been more difficult to attack. The US’s plan would have involved the insertion of a malicious worm into the facility’s computer system to cut its power.

The government has yet to clarify its prior offensive efforts or expand on its ability to conduct them. In the wake of the Sony attack, for example, Obama alluded to having retaliation possibilities at his disposal, but didn't elaborate on what exactly the US was capable of carrying out. This reported plan offers one of the most thorough looks at US cyberattack endeavors.

The New York Times reports that all aspects of Nitro Zeus have been shelved for the time being. Iran has already removed two-thirds of the centrifuges in Fordo since an agreement was reached this summer, and it’s banned from conducting nuclear work there for the next 15 years.