The Pentagon has revealed that the United States had held nuclear weapons on Okinawa, Japan during the Cold War.
According to a Department of Defense website, the Pentagon has declassified "the fact that US nuclear weapons were deployed on Okinawa prior to Okinawa's reversion to Japan on May 15, 1972."
The National Security Archive at George Washington University welcomed the declassification of the matter that had long been an open secret, according to AFP.
The institution, though, pointed to US Air Force photos which show nuclear weapons on the island that have been publicly available for more than 25 years.
"However welcome the release may be, its significance is somewhat tempered by (that) astonishing fact," the non-governmental research group said in a statement Friday.
The US government had wasted an "inordinate" amount of time and resources through postponing the declassification, the group added.
Okinawa remained under US control from 1945 to 1972, with many parts of the archipelago still being used for US bases.
During the final stage of the World War II, the US dropped the world's first deployed atomic bombs on Hiroshima and Nagasaki on August 6 and 9, 1945, respectively, leaving over 210,000 people dead almost immediately.
The horrible impacts of the bombings made Japan surrender on August 15, 1945, bringing an end to World War II. The blasts also ushered in the Cold War era, a period of heightened tension between the West and the former Soviet Union.
The atomic bombing killed around 140,000 people in Hiroshima, including those who died of radiation exposure or succumbed to their wounds.
Japan, as the only nation to have been attacked with nuclear weapons, has campaigned to abolish the weapons since 1945.