the establishment of offensive military forces, and in 1967 it adopted the Three Non-Nuclear Principles, ruling out the production, possession, or introduction of nuclear weapons. Despite this, the idea that Japan might become a nuclear power has persisted. After China's first nuclear test in 1964, Japanese Prime Minister Eisaku Satō said to President Lyndon Johnson when they met in January 1965, that if the Chinese Communists had nuclear weapons, the Japanese should also have them. This shocked Johnson's administration, especially when Sato added that "Japanese public opinion will not permit this at present, but I believe that the public, especially the younger generation, can be 'educated'." Throughout Sato's administration Japan continued to discuss the nuclear option. It was suggested that tactical nuclear weapons, as opposed to larger strategic weapons, could be defined as defensive, and therefore be allowed by the Japanese Constitution. A White Paper commissioned by future Prime Minister Yasuhiro Nakasone opined that it would be possible that possessing small-yield, purely defensive nuclear weapons would not violate the Constitution, but that in view of the danger of adverse foreign reaction and possible war, a policy would be followed of not acquiring nuclear weapons "at present". Nuclear Non-Proliferation Treaty The Johnson administration became anxious about Sato's intentions and made securing Japan's signature to the Nuclear Non-Proliferation Treaty (NPT) one of its top priorities. In December 1967, to reassure the Japanese public, Sato announced the adoption of the Three Non-Nuclear Principles. These were that Japan would not manufacture, possess, or permit nuclear weapons on Japanese soil. The principles, which were adopted by the Diet, but are not law, have remained the basis of Japan's nuclear policy ever since. According to Kei Wakaizumi, one of Sato's policy advisers, Sato realized soon after making the declaration that it might be too constraining. He therefore clarified the principles in a February 1968 address to the Diet by declaring the "Four Nuclear Policies" ("Four-Pillars Nuclear Policy"): Promotion of the peaceful use of nuclear energy Efforts towards global nuclear disarmament Reliance and dependence on US extended deterrence, based on the 1960 US-Japan Security Treaty Support for the "Three Non-Nuclear Principles under the circumstances where Japan's national security is guaranteed by the other three policies." It followed that if American assurance was ever removed or seemed unreliable, Japan might have no choice but to go nuclear. In other words, it kept the nuclear option available. In 1969