On 19 June 1941, Voronov was transferred to the post of Chief of the Main Directorate of Air Defence, who was now personally accountable to the People's Commissar of Defence. During the first days of the war on the Eastern Front; Voronov reinforced the air defence of Moscow. On 19 July, the post of chief of the artillery was restored and Voronov was appointed to that position. On 20 July, he was ordered organized antitank artillery during the Yelnya Offensive. After returning to Moscow, Voronov, together with Leonid Govorov, developed detailed instructions on antitank tactics, which was soon sent to the troops as a Stavka directive. As part of the State Defense Committee, Voronov went to Leningrad to organized antitank defence and the artillery. Through the efforts of Voronov, the GRAU became subordinate to the Chief of the Artillery. Voronov also set up an artillery headquarters, led by Ivan Susloparov.