A former senior U.S. official ruled out deploying nuclear weapons in Okinawa after the territory's return to Japanese administration in 1972, saying there was no strategic value in doing so, according to diplomatic records declassified on Wednesday.

As part of Okinawa's reversion, Prime Minister Eisaku Sato and President Richard Nixon had agreed that the United States would remove its nuclear arsenal from military bases on the islands, which lie hundreds of kilometers to the southwest of mainland Japan.

The agreement, reached in November 1969, was made necessary by public sentiment in Japan going back to the bombings of Hiroshima and Nagasaki, and Sato's adoption of the three non-nuclear principles of not possessing, not producing and not permitting the introduction of nuclear weapons.

(Declassified diplomatic records pictured on Dec. 17, 2019.)

But the leaders infamously made a secret arrangement -- the United States would be allowed to bring back the nuclear weapons if they were needed to counter threats from its Cold War rivals, the Soviet Union and China.

The former official's name has been redacted from the declassified records, but experts say it is likely to be Morton Halperin, a senior staff member of the National Security Council during the Nixon administration.

The remarks were made in a meeting on Dec. 9, 1969, with a Japanese Embassy official, and cast doubt on the necessity of such a secret arrangement.

The former official, described in the declassified records only as someone from the Washington-based think tank Brookings Institution, mentions that Japanese media had been reporting on the possibility of nuclear weapons being brought back to Okinawa in the event of an emergency.

This was something that had zero chance of happening, the former official said, explaining that in a situation that required a nuclear response, the United States would deploy B-52 bombers directly from its base on Guam or launch them from Polaris submarines.

But the secret arrangement was necessary to appease the U.S. military, which was concerned that permanently losing one of its options for forward deployment would hurt its ability to respond to threats quickly, they said.

(Eisaku Sato and Richard Nixon at White House in November 1969.)

The former official said the United States' nuclear arsenal in South Korea was more than enough to counter threats from North Korea, but added that regarding possible retaliation by the Soviet Union or China, any attack against Japan would be carried out on the mainland regardless of whether there were any nuclear weapons in Okinawa.

On the question of whether the nuclear withdrawal from Okinawa would inaccurately signal a decrease in U.S. commitment to Japan's security, the former official said such concerns were unfounded because both the Soviet Union and China were aware that the United States had been placing more emphasis on conventional weapons.

Takuma Nakashima, an associate professor of Japanese political and diplomatic history at Kyushu University, said the remarks cast new light on negotiations to return Okinawa to Japanese administration.

Sato and Nixon "went as far as to make a secret arrangement on the nukes in Okinawa, but militarily speaking, an environment was about to be created where they could be removed," Nakashima said.