Concerns intensified that a Russian-occupied nuclear reactor in southern Ukraine could be the target of fresh attacks as Kyiv and Moscow traded accusations over the threat of a radiological incident. Ukrainian President Volodymyr Zelenskiy reinforced a warning overnight that Russia may be planning to sabotage the Zaporizhzhia Nuclear Power Plant, which Moscow’s forces have occupied since the start of the war. The Kremlin responded July 5 that the government in Kyiv is planning a provocation.

“We have information from our intelligence that Russian troops have placed objects resembling explosives on the roof of several power units” at Zaporizhzhia, Zelenskiy said in his nightly address to the nation. The objects may also be used to “simulate” an attack, he said.

Inspectors from the United Nations International Atomic Energy Agency (IAEA) have reported that they’ve seen no evidence so far of mines or explosives. IAEA director General Rafael Mariano Grossi said on July 5 that his team had requested access to the rooftops of two reactors and other parts of the complex following the accusations of mining.

The nuclear plant, the largest in Europe, has been the target of artillery, drone and rocket attacks on and off for more than a year, with Ukrainian and Russian official blaming each other for the strikes. UN monitors were installed at Zaporizhzhia in September in order to assess risks. 

A U.S. Air Force decision to dispatch its Boeing WC-135R Constant Phoenix aircraft to Greece on June 30 has fuelled speculation that it could be linked with threats to Zaporizhzhia. The aircraft, which can register radioactive releases in real time, played a crucial role in detecting debris from the 1986 Chernobyl nuclear meltdowns, according to the Air Force. 

The Pentagon didn’t immediately return requests for comment. The Air Force has said the aircraft is routinely deployed in the Mediterranean Sea.