On the domestic front, he covertly opposed Joseph McCarthy and contributed to the end of McCarthyism by openly invoking the modern expanded version of executive privilege. He otherwise left most political activity to his Vice President, Richard Nixon. He was a moderate conservative who continued New Deal agencies and expanded Social Security. He also launched the Interstate Highway System, the Defense Advanced Research Projects Agency (DARPA), the establishment of strong science education via the National Defense Education Act, and encouraged peaceful use of nuclear power via amendments to the Atomic Energy Act.