Pyongyang, September 22 (KCNA) -- It has been revealed that the U.S. had introduced nuclear weapons in the Philippines without its permission.

According to a confidential document acquired by the "National Secret Archive," a research institute of George Washington University, the U.S. kept nuclear weapons in the Philippines for about four years from 1966, the Japanese Mainichi Shimbun reported on September 16.

Contained in the document is a fear that if the introduction of nuclear weapons was known to the Philippine side, the bilateral relations would be deteriorated, the newspaper said. The fact shows the U.S. kept the nuke deployment secret at that time.