Answer
Roman von Ungern-Sternberg was accused of counter-revolution during his trial, as he had sought to overthrow the Soviet regime in Mongolia. Ungern-Sternberg had been a White Army general during the Russian Civil War, and he had fought against the Bolsheviks. After the civil war, he had fled to Mongolia, where he had established an independent state. In 1921, the Soviet Union invaded Mongolia and overthrew Ungern-Sternberg's government.