As rebellious Wagner forces drove north toward Moscow on June 24, a contingent of military vehicles diverted east on a highway in the direction of a fortified Russian army base that holds nuclear weapons, according to videos posted online and interviews with local residents.

Once the Wagner fighters reach more rural regions, the surveillance trail goes cold – about 100 km from the nuclear base, Voronezh-45. Reuters could not confirm what happened next, and Western officials have repeatedly said that Russia’s nuclear stockpile was never in danger during the uprising, which ended quickly and mysteriously later that day.

But in an exclusive interview, Ukraine’s head of military intelligence, Kyrylo Budanov, said that the Wagner fighters went far further. He said that they reached the nuclear base and that their intention was to acquire small Soviet-era nuclear devices in order to “raise the stakes” in their mutiny. “Because if you are prepared to fight until the last man standing, this is one of the facilities that significantly raises the stakes,” Budanov said.

The only barrier between the Wagner fighters and nuclear weapons, Budanov said, were the doors to the nuclear storage facility. “The doors of the storage were closed and they didn’t get into the technical section,” he said.

Reuters was not able to independently determine if Wagner fighters made it to Voronezh-45. Budanov did not provide evidence for his assertion and he declined to say what discussions, if any, had taken place with the United States and other allies about the incident. He also didn’t say why the fighters subsequently withdrew.

A source close to the Kremlin with military ties corroborated parts of Budanov’s account. A Wagner contingent “managed to get into a zone of special interest, as a result of which the Americans got agitated because nuclear munitions are stored there,” this person said, without elaborating further.