David Slater, 64, a retired US Army lieutenant colonel, pleaded guilty in July to transmitting secret information on the platform to someone "who claimed to be a female living in Ukraine."

Slater was working at the time as a civilian assigned to the US Strategic Command in Nebraska, whose portfolio includes nuclear deterrence.

The documents, some of which were classified as "top secret," concerned the war in Ukraine, including military targets and Russian military capabilities, according to the Justice Department.

A federal judge in Nebraska sentenced Slater to 70 months in prison on Wednesday and a $25,000 fine.