The Foreign Ministry has decided to admit the existence of a secret Japan-U.S. pact under which Tokyo allows stopovers of U.S. military ships and aircraft carrying nuclear weapons, ministry sources said Nov. 21.

Foreign Minister Katsuya Okada speaks at a news conference at the Foreign Ministry on Nov. 21. KYODO PHOTO

During an in-house probe, the ministry found documents suggesting the existence of the secret nuclear agreement, according to the sources.

Previous governments led by the Liberal Democratic Party consistently denied the existence of the secret nuclear pact, but the new Democratic Party of Japan-led administration is to officially change that stance.

"The probe is in the final stage and we will announce the outcome in January," Foreign Minister Katsuya Okada said, although he declined to reveal details.

A third-party committee consisting of experts will analyze the findings, according to the ministry.

According to the comprehensive 1960 Japan-U.S. Security Treaty, Washington is required to consult with Tokyo before bringing nuclear weapons into Japan. However, the ministry has determined the newly found documents indicate that stopovers of U.S. vessels and aircraft carrying nuclear weapons are not subject to prior consultation, the sources said.

The documents have already been disclosed in the United States.

The in-house probe has been conducted under the instruction of Okada, who after assuming his post in September ordered the ministry to look into purported bilateral secret pacts — two related to the revision of the security treaty and two related to the 1972 reversion of Okinawa to Japanese sovereignty from U.S. control.