Archive · 19 Aug 2026
US Warns of Attacks on Siemens Devices in Water Systems
US officials say hackers are trying to break into Siemens devices used to control important infrastructure.
These devices help operate water plants and other facilities.
If hackers take control, they could interrupt services or damage equipment.
People could also lose access to important data.
The warning applies to Siemens S7 Series controllers in several industries.
Officials say hackers may be using artificial intelligence to make attacks easier to create.
Recent water-system incidents in several states may be connected to Iran, according to cybersecurity experts.
However, the government has not officially blamed Iran.
President Donald Trump said he did not think Iran was responsible and blamed Minnesota instead.
US agencies warned of an active threat targeting Siemens S7 Series programmable logic controllers.
The devices monitor and operate systems in water, energy, manufacturing and other critical sectors.
Officials said successful compromises could cause disruptions, safety incidents, equipment damage or data breaches.
The warning follows recent cyber incidents affecting local water systems that experts suspect may be Iran-linked.
Federal agencies have not formally attributed the attacks to Iran, while Donald Trump said Iran was not involved and blamed Minnesota.
- Who
- The National Security Agency, Federal Bureau of Investigation, United States Department of Energy, United States Environmental Protection Agency, United States Department of Homeland Security and Cybersecurity and Infrastructure Security Agency warned about unidentified hackers; President Donald Trump disputed suspected Iranian involvement.
- What
- Officials warned of an active threat targeting Siemens S7 Series programmable logic controllers used in critical infrastructure.
- When
- The advisory was published on Wednesday; related advisories were issued July 22 and July 30, and reported water-system incidents occurred July 26 and July 27.
- Where
- The threat affects critical infrastructure in the United States, including water and wastewater facilities and systems in multiple states.
- Why
- Compromised controllers could disrupt processes, cause safety incidents, damage equipment, expose sensitive data and create cascading effects across connected systems.
Federal Cybersecurity Assessment
Donald Trump’s Position
Iran’s possible involvement
Federal Cybersecurity Assessment
Cybersecurity experts suspect recent attacks on local water systems may be linked to Iran, and a July 22 advisory warned about Iranian-affiliated hackers targeting programmable logic controllers.
Donald Trump’s Position
Donald Trump said on July 31 that he did not believe Iran was involved and blamed Minnesota for the reported wave of water-related cyber incidents.
Public attribution
Federal Cybersecurity Assessment
Federal officials warned about the active threat but have not formally attributed the recent water-system attacks to Iran.
Donald Trump’s Position
Trump rejected the suspected Iran connection despite the federal warnings and expert assessments.
- Targeted devices
- Siemens S7 Series programmable logic controllers
- Affected sectors
- Manufacturing, energy, water and wastewater, chemical, food and agriculture
- Threat status
- The advisory describes an active threat
- Potential impacts
- Process disruption, safety incidents, downtime, equipment damage, sensitive-data compromise and cascading effects
- Suspected connection
- Cybersecurity experts suspect some recent water-system attacks may be linked to Iran
- Federal attribution
- US officials have stopped short of formally linking the recent water-system attacks to Iran
- Related advisories
- CISA warned on July 30 about increased targeting of programmable logic controllers, following a July 22 warning about Iranian-affiliated hackers