The United States government has issued a warning that Iran-backed hackers are intensifying attacks on American critical infrastructure, posing growing operational and financial risks.

In a joint advisory released Tuesday, the FBI, National Security Agency, Cybersecurity and Infrastructure Security Agency, and the Department of Energy cautioned that Iranian government-affiliated actors are exploiting internet-facing systems across multiple sectors.

Key targets include water and wastewater utilities, energy networks, and local government operations.

While the agencies did not disclose specific organizations, they emphasized that the intrusions are designed to create “disruptive effects within the United States,” with some attacks already resulting in operational disruptions and financial losses.

The advisory follows a provocative social media post by U.S. President Donald Trump earlier Tuesday, in which he warned Iran that “a whole civilization will die tonight” unless it agrees to a deal to reopen the Strait of Hormuz, a strategic chokepoint for global shipping, by the end of the day.

Since the onset of the conflict, the Iranian government–linked hacking group Handala has been tied to multiple high-profile cyberattacks.

Notably, the group carried out a disruptive breach at U.S. medical technology firm Stryker, remotely wiping thousands of employee devices using the company’s own security systems.