As President of the United States for two terms, Eisenhower had slowed the push for increased defense spending despite pressure to build more military equipment during the Cold War arms race. Nonetheless, the American military services and the defense industry had expanded a great deal in the 1950s.
Although he thought this growth was needed to counter the Soviet Union, it confounded Eisenhower. With his credibility and standing as a military leader, in his farewell speech he was able to stand up to powerful interests and describe them as a necessary evil.
Source: National Archives