For Operation Downfall, the US military envisaged requiring more than 30 divisions for a successful invasion of the Japanese home islands. In comparison, the Soviet Union had about 11 divisions available, comparable to the 14 divisions the US that estimated it would require to invade southern Kyushu. The Soviet invasion of the Kuril Islands (18 August – 1 September 1945) took place after Japan's capitulation on 15 August. However, the Japanese forces in those islands resisted quite fiercely although some of them proved unwilling to fight after Japan's surrender on 15 August. In the Battle of Shumshu (18–23 August 1945), the Soviet Red Army had 8,821 troops that were not supported by tanks and without back-up from larger warships. The well-established Japanese garrison had 8,500 troops and fielded about 77 tanks. The battle lasted one day, with minor combat actions going on for four more after the official surrender of Japan and the garrison, during which the attacking Soviet forces lost over 516 troops and five of the 16 landing ships (many of these formerly belonged to the US Navy and were later given to the Soviet Union) to Japanese coastal artillery, and the Japanese lost over 256 troops. Soviet casualties during the Battle of Shumshu totaled up to 1,567, and the Japanese suffered 1,018 casualties, making Shumshu the only battle in the 1945 Soviet–Japanese War in which Soviet losses exceeded those of the Japanese, in stark contrast to overall Soviet-Japanese casualty rates in land-based fighting in Manchuria.