The U.S. began launching strategic bombing raids on Japan from the Mariana Islands in November 1944, but Japan still controlled several islands that provided defense for the Japanese archipelago. In February 1945, the U.S. launched an invasion of the well-defended island of Iwo Jima, taking control of that island the following month. On April 1, the U.S. landed on Okinawa Island, the largest of the Ryukyu Islands. The Japanese allowed the Americans to land on the island before launching a fierce attack that included "kamikaze" suicide attacks by Japanese aircraft. Japanese forces on Okinawa held out until June 1945; U.S. forces suffered over 60,000 casualties during the operation.