After the Guadalcanal Campaign, the Allies initiated several operations against Japan in the Pacific. In May 1943, Canadian and US forces were sent to eliminate Japanese forces from the Aleutians. Soon after, the United States, with support from Australia, New Zealand and Pacific Islander forces, began major ground, sea and air operations to isolate Rabaul by capturing surrounding islands, and breach the Japanese Central Pacific perimeter at the Gilbert and Marshall Islands. By the end of March 1944, the Allies had completed both of these objectives and had also neutralised the major Japanese base at Truk in the Caroline Islands. In April, the Allies launched an operation to retake Western New Guinea.