At the beginning of World War I, Japan assumed control of the Marshall Islands. The Japanese headquarters was established at the German center of administration, Jaluit. On January 31, 1944 American forces landed on Kwajalein atoll and U.S. Marines and Army troops later took control of the islands from the Japanese on February 3, following intense fighting on Kwajalein and Enewetak atolls. In 1947, the United States, as the occupying power, entered into an agreement with the UN Security Council to administer much of Micronesia, including the Marshall Islands, as the Trust Territory of the Pacific Islands.