favoring non-nuclearization, the document concluded that the U.S. nuclear deterrent sufficed to deter outside aggression. It also stressed both Japan's extreme vulnerability to nuclear attack (high population density) and the likelihood of international isolation in the wake of a nuclear weapons program. Though Satō thought little of the principles and was pliant in his enforcement of the principle of nonintroduction, in view of popular opinion and the embracing of the policy by the rival Social Democratic Party, he and the LDP also remained vocally supportive. In 1970, as desired by the U.S. but after much hesitation and with some key stipulations, Japan signed the NPT; and in 1972, relieved of U.S. nuclear weapons, Okinawa reverted to Japanese rule. The Diet passed a resolution formally adopting the principles in 1971, though they were not made law. Eisaku Satō was presented with the Nobel Peace Prize in 1974, in large part for his work toward Japan's entry into the NPT. In his Nobel Lecture (on the seventh anniversary of his original statement to the Diet), Satō reiterated and discussed the Three Non-Nuclear Principles and expressed hope and confidence that future governments would adopt them as well. Further influence Opinion polls have consistently revealed that public opinion is overwhelmingly opposed to nuclearization, as several events over the decades following World War II, even after the end of the Cold War, have demonstrated. The Kobe Formula The port of Kobe was used heavily by the U.S. fleet during its postwar occupation, which ended in 1974. Throughout the occupation, U.S. military facilities at Kobe Port were the target of continuous public protest. Public petitions after Kobe's return to Japan culminated in an 18 March 1975 resolution by the city council to prohibit nuclear-armed vessels from entering the port. U.S. policy being to neither confirm nor deny nuclear weapons deployment, this resolution effectively removed the U.S. naval presence from Kobe Port. Amid the presence of nuclear-powered U.S. vessels and concerns that the government allowed nuclear-armed warships into Japanese ports (later confirmed), this resolution became the first major application of the three non-nuclear principles. The strict policy has become known as the "Kobe Formula", and since its inception several thousand Japanese municipalities have adopted similar nuclear-free resolutions. Review In recent years Japanese policymakers have been increasingly public in calling the three non-nuclear principles into question. In October 1999, Deputy Vice Minister of Defense Shingo Nishimura proposed to