In 1958 the United States secretly conducted a low-yield, high-atmosphere nuclear weapon effects test in the South Atlantic code-named ARGUS. It tested a theory devised by Nicholas Christofilos that an anti-missile shield could be created around the planet by trapping high-energy electrons in the Earth’s radiation field. In order to conduct the test before the October 1958 nuclear test moratorium, the military borrowed International Geophysical Year equipment and used the program as cover for the clandestine nuclear tests. Though the experiment determined that an electron shield could not work, it provided important research data for weapon effects, atmospheric physics, and long-distance communications. In March 1959, Hanson Baldwin and Walter Sullivan of the New York Times published an unauthorized account of the tests. In response, the White House presented ARGUS as a civilian science program of the International Geophysical Year rather than a nuclear weapon effects test. In the internal debate about declassification, in the publicity of the test, and in the memories of James Killian and Herbert York, Operation ARGUS demonstrates that many scientists and Americans remained comfortable with anti-militarism, even under militarized policies.