Barnes was engaged in a legal dispute with his Russian ex-wife over the custody of the boys.
A Moscow court on Tuesday sentenced a 65-year-old American to 21 years in prison for sexually assaulting his own sons when they lived in the United States.
"The Savelovsky court of Moscow sentenced 65-year-old US citizen David Thomas Barnes to 21 years in a penal colony, finding him guilty of sexually abusing his own children," the court said on social media.
Barnes was engaged in a legal dispute with his Russian ex-wife over the custody of the boys.
Russian prosecutors accuse him of sexually abusing the two boys between 2014 and 2018 when they lived in Texas and both were less than six years old.
The Texan was detained in Moscow in January 2022, weeks before Russia's Ukraine offensive.
Russian news agencies said Barnes's ex-wife accused him of sexually abusing their two sons several years ago while living in the US.
His family has told US media he is innocent and that his ex-wife took their children to Russia without his consent.
Several Americans are held in prison in Russia.
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