The Bolsheviks were being assaulted by forces from the reactionary wing of Romanov monarchists, reformist Social Democrats, former Imperial Army officers and soldiers in the anti-communist White Armies along with several foreign nations sending in interventionist forces, aid and supplies for the White Armies. Despite this, Vladimir Lenin regarded the left-wing opposition as the most threatening the Bolshevik regime faced. [...] The authority the Bolsheviks commanded, such as the Cheka and other exertions of control and supremacy were primarily used against left-wing oppositionists rather than the reactionary counter-revolution.