State officials in Minnesota reported that at least 36 water systems were breached in a coordinated campaign over Sunday and Monday. The intrusions focused on disruption rather than financial gain, with no ransom demand, and early assessments indicate the water remains safe to drink. The Cybersecurity and Infrastructure Security Agency (CISA) had published an advisory in April warning that pro-Iranian hackers were targeting US water and energy infrastructure in retaliation for the war that began on 28 February. Late on Thursday, the FBI said hackers had targeted water facilities in at least seven states.

During a cabinet meeting at the presidential retreat, Trump disputed the initial findings linking Iran to the attacks. "We heard in Minnesota there was a cyberattack, and they blame it on Iran. I don't think so," he told reporters. He went on to accuse Minnesota of being behind the breaches. "I think Minnesota is behind it. You know who's behind it? Minnesota. Because they're grossly incompetent. I think the governor is behind it. I don't think there was an Iranian cyber attack." The president offered no evidence for his assertions.

“I think I blame it on Minnesota because they're grossly incompetent. I would blame it on Minnesota and the governor, the corrupt governor of Minnesota. Iran's got bigger problems than worrying about Minnesota.”

The remarks continue a long-running feud between Trump and Walz, who was Kamala Harris's running mate in the 2024 election. The White House, asked for evidence to support the president's claims, referred to his cabinet meeting comments.

Governor Walz responded sharply on social media. "Trump knows exactly who is responsible for this attack, and knows that other states were hit too," he wrote. "This is what modern warfare looks like, and it further illustrates there's no plan to win a war with Iran."

“Trump knows exactly who is responsible for this attack, and knows that other states were hit too. This is what modern warfare looks like, and it further illustrates there's no plan to win a war with Iran.”

Investigators cautioned that their assessments are preliminary and could change as more data is examined, but nothing had surfaced by Friday to challenge the prevailing view that Iran is likely responsible. Cynthia Kaiser, former deputy assistant director of the FBI's cyber division, told the Associated Press that Iran has the "geopolitical motivations" and a recent history of targeting water systems. "I think most credible researchers and responders would be right to treat it like it's Iran until proven otherwise," she said. The FBI, CISA and other agencies had issued an advisory last week warning that Iranian hackers have been focused on such systems.

If confirmed, the hacking spree would be one of the most significant cyberattacks of the conflict and one of the most serious efforts to compromise US water systems on record. Digital warfare has become ingrained in military conflict, and local water plants often lack the resources to install the latest security patches, making them a favoured target both for ease of access and the disruption they can cause.