These facilities, in particular the airfields and naval bases, played a key role in the defense of Alaska, and in military operations against Japanese forces which occupied Attu and Kiska, two remote islands in the Aleutian chain.

In 1939 Congress appropriate funds for the construction of naval air stations at Sitka and other sites in coastal Alaska.

To facilitate this work, a causeway 8,100 feet (2,500 m) in length was constructed connecting Japonski to Mahknati via this island chain.

[3] The naval facilities on Japonski Island eventually grew to include several hangars, ramps into the water to facilitate the movement of seaplanes onto land, a large concrete parking area, a control tower, two piers, and a number of ancillary support buildings.

[3] The surviving elements of the Sitka Naval Operating Base, the causeway to Makhnati Island, and the coastal defense station were designated a National Historic Landmark on August 11, 1986.