This policy of nuclear abstention was justified internally by the "1968/1970 Report", the product of a secret study commissioned by the Satō Government (leaked to the public in 1994). The document was a comprehensive cost-benefit analysis of the nuclear option from technical, economic, political, and international perspectives. Ultimately 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.