The U.S. government weighed its chances of convincing Tokyo in the late 1960s to allow the deployment of nuclear weapons in Japan if a crisis in East Asia were to break out, according to newly declassified documents.

The idea, which was never proposed because its chances of success were apparently considered “very slight,” offers a look into how Washington sought to expand its military footprint in the region after World War II and the Korean War.

The atomic bombings of Hiroshima and Nagasaki had left the Japanese public with a strong aversion to nuclear weapons, with the prohibition of their possession, manufacture and introduction in Japanese territory — first outlined in 1967 — coming to form the core of Japan’s nuclear policy.

The documents, dated June 26, 1969, are composed of drafts of a joint communique by the leaders at the time — President Richard Nixon and Prime Minister Eisaku Sato.

The documents outlined the role of the U.S. military after the return of Okinawa to Japanese administration in 1972.

One of the drafts noted that if the two countries agreed that if a “state of emergency existed in East Asia threatening imminent armed attack” on Japan, steps would be taken to “enable the U.S. forces in Japan to introduce the necessary forces and equipment to meet the danger.”

While the two countries eventually made a secret agreement allowing the introduction of nuclear weapons to the southern islands even after the handover, the documents reveal for the first time that the U.S. government had a desire to deploy part of its nuclear arsenal in Honshu, according to Masaaki Gabe, a professor at the University of the Ryukyus in Okinawa.

The draft, written by the U.S. State Department, is labeled as “including all of the points desired by the U.S. . . . whose chance of full acceptance by the GOJ (government of Japan) is very slight.”

Gabe obtained the previously top secret documents from the U.S. National Archives.

The documents also include a separate draft of the joint communique that the State Department saw as “possibly more acceptable” to Japan.