westernmost group of the Aleutian Islands, southwestern Alaska, U.S. The islands lie about 1,500 miles (2,400 km) west of the tip of the Alaska Peninsula. The two largest islands in the group are Attu and Agattu. Eareckson Air Station (formerly Shemya Station), a strategic refueling location for military aircraft, is located on Shemya Island. Attu, the westernmost island of the Aleutian chain, was one of several U.S. islands occupied by Japan during World War II. The Near Islands form the westernmost extension of the Alaska Maritime National Wildlife Refuge.