NSC-68 outlined a variety of possible courses of action, including a return to isolationism; war; continued diplomatic efforts to negotiate with the Soviets; or "the rapid building up of the political, economic, and military strength of the free world." This last approach would allow the United States to attain sufficient strength to deter Soviet aggression. In the event that an armed conflict with the Communist bloc did arise, the United States could then successfully defend its territory and overseas interests.
The authors of NSC-68 rejected a renewal of U.S. isolationism, fearing that this would lead to the Soviet domination of Eurasia, and leave the United States marooned on the Western Hemisphere, cut off from the allies and resources it needed to fend off further Soviet encroachments. The report also ruled out a preventive strike against the Soviet Union, because its authors reckoned that such action would not destroy the Soviet military's offensive capacities, and would instead invite retaliatory strikes that would devastate Western Europe. Moreover, U.S. experts did not believe that American public opinion would support measures that might lead to a protracted war. NSC-68 did not rule out the prospect of negotiating with the Soviet Union when it suited the objectives of the United States and its allies; however, the report's authors argued that such an approach would only succeed if the United States could create "political and economic conditions in the free world" sufficient to deter the Soviet Union from pursuing a military solution to the Cold War rivalry.
NSC-68 concluded that the only plausible way to deter the Soviet Union was for President Harry Truman to support a massive build-up of both conventional and nuclear arms. More specifically, such a program should seek to protect the United States and its allies from Soviet land and air attacks, maintain lines of communications, and enhance the technical superiority of the United States through "an accelerated exploitation of [its] scientific potential." In order to fund the substantial increase in military spending this conclusion demanded, the report suggested that the Government increase taxes and reduce other expenditures.
Initially, a number of U.S. officials strongly opposed NSC-68's recommendations. Critics such as Secretary of Defense Louis Johnson, and senior diplomats such as Soviet experts and former ambassadors to the Soviet Union George Kennan and Charles Bohlen, argued that the United States already had a substantial military advantage over the Soviet Union. Kennan, in particular, disagreed with Nitze's assertion that the Soviet Union was bent on achieving domination through force of arms, and argued that the United States could contain the Soviet Union through political and economic measures, rather than purely military ones. However, the invasion of South Korea by Soviet and Chinese-backed North Korean forces in June 1950, and continuing charges by Congressional critics that the Administration was soft on Communism, quickly settled matters in favor of the report's recommendations. NSC 68's recommendations thereby became policy, and the United States Government began a massive military build-up. While NSC-68 did not make any specific recommendations regarding the proposed increase in defense expenditures, the Truman Administration almost tripled defense spending as a percentage of the gross domestic product between 1950 and 1953 (from 5 to 14.2 percent).