The FBI has warned law enforcement agencies in California that Iran may be planning a surprise drone attack launched from an unidentified vessel off the West Coast, according to an internal alert reviewed by ABC News.

The bulletin, distributed at the end of February, states that as of early February 2026, Iran "allegedly aspired to conduct a surprise attack using unmanned aerial vehicles from an unidentified vessel off the coast of the United States Homeland, specifically against unspecified targets in California, in the event that the US conducted strikes against Iran." The alert added that authorities have "no additional information on the timing, method, target, or perpetrators of this alleged attack."

The warning came as the Trump administration launched its ongoing military campaign against Iran, known as Operation Epic Fury, which began with coordinated U.S.-Israeli strikes on February 28. Since then, Iran has fired at least 380 missiles and more than 1,480 drones at Gulf Arab nations, according to an Associated Press tally. Six U.S. soldiers were killed in Kuwait when an Iranian drone struck an operations center at a civilian port.

A spokeswoman for the FBI's Los Angeles office declined to comment. The White House did not immediately respond to a request for comment.

White House spokeswoman Anna Kelly defended the administration's approach, saying "Iran's retaliatory ballistic missile attacks have decreased by 90% because Operation Epic Fury is crushing their ability to shoot these weapons or produce more."

The drone threat alert is part of a broader wave of warnings from U.S. intelligence agencies. The Department of Homeland Security (DHS) has issued a separate bulletin warning of a "heightened threat environment" following the killing of Iranian Supreme Leader Ayatollah Ali Khamenei. That bulletin noted that two senior Iranian religious leaders issued fatwas calling on Muslims worldwide to seek revenge for Khamenei's death.

In addition to physical threats, the FBI and National Security Agency have warned U.S. defense contractors that "Iranian-affiliated cyber actors may target U.S. devices and networks for near-term cyber operations," with companies tied to Israeli defense and research firms considered at the highest risk.

Security experts warn that the dangers could grow the longer the conflict drags on. According to the Council on Foreign Relations, the extended conflict increases Iran's incentive to use "all forms of asymmetric warfare," including sleeper agents, lone-wolf attacks, cyberattacks on infrastructure, and physical strikes on U.S. soil. The council's senior fellow for counterterrorism and homeland security, Bruce Hoffman, also raised concerns that recent federal workforce cuts — including the dismissal of FBI counterintelligence agents who had monitored Iranian threats — may have weakened the country's ability to respond.

Gulf Arab allies, meanwhile, have expressed frustration with how the U.S. has handled the conflict. Officials from two Gulf nations told the AP they were not given advance notice of the February 28 strikes and complained the U.S. had ignored their warnings about regional fallout. One official said his country's stock of missile interceptors was "rapidly depleting."

Former Saudi intelligence chief Prince Turki al-Faisal told CNN that "this is Netanyahu's war," referring to Israeli Prime Minister Benjamin Netanyahu, adding that Netanyahu "somehow convinced the president (Trump) to support his views."

Pentagon officials have acknowledged in closed-door briefings with lawmakers that U.S. forces are struggling to intercept Iran's waves of low-cost drones, particularly the Shahed models. Defense Secretary Pete Hegseth and Joint Chiefs Chairman Gen. Dan Caine told lawmakers the U.S. will not be able to stop many of the incoming unmanned aerial vehicles (UAVs). The U.S. has even sought anti-drone expertise from Ukraine, which has extensive experience countering Iran's Shahed drones. President Trump told Reuters he would welcome that help, saying, "Certainly, I'll take, you know, any assistance from any country."

Looking ahead, Hoffman flagged the summer months as a particularly high-risk period, noting that upcoming high-profile events — including World Cup soccer matches and celebrations marking the 250th anniversary of U.S. independence — could present Iran with "ideal opportunities to simultaneously exact revenge and embarrass the United States."