When were Iwo-Jima and Okinawa returned to Japanese sovereignty?

Okinawa and the surrounding Ryukyu Islands were returned to Japan on May 15, 1972. Iwo-Jima, part of the Bonin Islands, was returned earlier on June 26, 1968.

Both islands were under American control after being captured during World War II. Both were the sites of some of the bloodiest battles of the Pacific theater of WWII and, perhaps, of the entire war. The United States retained administrative control over these territories, even after the treaty of San Francisco, signed in 1951, which officially ended the postwar occupation of Japan. The return of these islands was a significant step in the post-war relationship between the two countries, with Okinawa's return, in particular, being a key diplomatic goal for Japan.

https://www.sarantakes.com/PDF%20Other%20Writings/B5-JAEAR.pdf