The United States announced new sanctions Friday aimed at the Iranian Revolutionary Guard, as Washington prepares retaliation after a strike killing three Americans in Jordan that was blamed on Iran-backed militias.

The US Treasury Department said it was imposing sanctions on six officials in the cyber-electronic command of the Iranian Islamic Revolutionary Guard Corps (IRGC), over activities targeting critical infrastructure.

In a separate notice, the Treasury added that it was also hitting a network of suppliers providing "materials and sensitive technology for Iran's ballistic missile and Unmanned Aerial Vehicle (UAV) programs."

The moves come shortly after President Joe Biden blamed "radical Iran-backed militant groups operating in Syria and Iraq" for the Sunday drone attack on a base in Jordan that killed three American troops.

He has pledged to hold "all those responsible to account at a time and in a manner of our choosing."

The casualties were the first US military deaths in an attack in the region since the Israel-Hamas war started.

But Iran said it had nothing to do with the strike, with its president vowing it would "respond firmly" to any attack.

In issuing the latest US sanctions on Friday, the Treasury said IRGC-affiliated cyber actors recently hacked and posted images on screens of controllers manufactured by an Israeli company, Unitronics.

"Unauthorized access to critical infrastructure systems can enable actions that harm the public and cause devastating humanitarian consequences," the department said.

A State Department spokeserson added that "actors used default credentials to display an anti-Israel message" on the controllers' interface.

Separately, the United States sanctioned four Iran- and Hong Kong-based entities, saying they "operated as covert procurement entities" for individuals actively supporting Iranian military organizations like the IRGC.

Another target was Hong Kong-based China Oil and Petroleum Company, allegedly involved in selling "hundreds of millions of dollars' worth of Iranian commodities" for the benefit of the IRGC Quds Force -- the foreign operations arm of the Revolutionary Guards.

As a result of the sanctions, all property of designated individuals in the United States is blocked and must be reported.