Following the Doolittle Raid, the next air attacks on Japan were made against the Kuril Islands in mid-1943. The liberation of Alaska's Attu Island in May 1943 during the Aleutian Islands Campaign provided the USAAF with bases within range of the Kurils. As part of the preparations for the liberation of Kiska Island in the Aleutians, the Eleventh Air Force conducted a series of raids against the Kurils to suppress the Japanese air units stationed there. The first of these attacks was made against southern Shumshu and northern Paramushiru by eight B-25s on 10 July. The Kurils were attacked again on 18 July by six B-24 Liberator heavy bombers, and the unopposed liberation of Kiska (Operation Cottage) took place on 15 August.