The Zaporizhzhia nuclear power plant in Ukraine apparently contains secret U.S. nuclear technology, which is why the United States has warned Moscow not to touch it.
This warning about sensitive nuclear technology that is physically located in the Zaporizhzhia power plant was officially stated in a letter from the U.S. Department of Energy sent to the Russian state company Rosatom on March 17, 2003, according to the article published by CNN which refers to a Ukrainian media resource RBC Ukraine.
It is not known what specific American technologies are deployed in the Ukrainian energy facility.
Director of the Department of Energy’s Office of Nonproliferation Policy, Andrea Ferkile wrote in a letter to the CEO of a Russian state-owned company Rosatom that Ukraine’s Zaporozhye nuclear power plant “contains US-origin nuclear technical data that is export-controlled by the United States Government.”
The letter explicitly noted that goods, software, and technology are subject to US export controls, particularly when there is a potential for their use in a manner that harms US national security interests.
The Ukrainian nuclear power plant is still operated and maintained by Ukrainian workers and nuclear specialists. However, the facility is de facto controlled by Rosatom after it was occupied by the invading Russian army.
This is probably the first publicly known case when the U.S. Department of Energy has warned the Russian state-owned company that any actions by citizens or organizations of the Russian Federation with American technology which is present in Ukraine are illegal.