The Baltic News Service said the court in Tallinn ruled that 38-year-old Deniss Metsavas - a former major with the Estonian army - and his father, 65-year-old Pjotr Volin, sold classified information to Russia's military intelligence service, the GRU.
The news service says the court found that Metsavas passed information along for a decade and sentenced him to 15½ years in prison. Volin worked with the GRU for approximately half as long and received a six-year prison term.
Metsavas, a fluent Russian-speaker, served with Estonia's armed forces for years in various positions including a mission with NATO troops in Afghanistan. He advanced to the rank of major in 2015 and was lately posted at the armed forces headquarters in Tallinn, the Estonian capital.
Estonian media say Volin served with the Soviet military from 1971 to 1979.
Estonia, a small Baltic nation of 1.3 million and current NATO member, borders Russia and was a former Soviet republic. It has had several high-profile spying cases since the country declared independence in 1991. Both Estonian and Russian citizens have been accused of providing sensitive information to Moscow.
Russia has remained highly interested in the domestic affairs of Estonia and its Baltic neighbors Latvia and Lithuania, particularly on military and security matters, and especially after they joined NATO in 2004.
There was no immediate comment from Moscow on the Estonian spying case.
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