On August 30, 1961, Russian Premier Nikita Khrushchev announced the end of a three-year moratorium on nuclear testing and Soviet tests recommenced on September 1st, initiating a series of tests that included the detonation of the Tsar bombs. In response to the announcement, President John F. Kennedy authorized Operation Dominic, which would later become the largest nuclear weapons testing program ever conducted by the United States, and the last atmospheric test series conducted by the U.S.
B Battery participated in a test named “Tightrope” on November 4, 1962 from the Johnston Atoll with between 1–40 kiloton W31 warheads in Operation Fishbowl. The successful kill at 21 km (69000 ft) altitude, the Nike Hercules missile test is regarded to be the last true US atmospheric nuclear test. Upon returning from the Pacific, B Battery was located just outside the entrance to Everglades National Park, the site being designated as HM-66, adjacent to A Battery.
In 1965, B Battery was relocated to a permanent site on North Key Largo, built by the Army Corps of Engineers and re-designated HM-40. When the site was first built, the highway was on the east side of the site and was actually the original State Road 4A. As the nearby community of Ocean Reef grew, the road was upgraded for a more direct route, built just west of the IFC site putting it in a triangle surrounded by roads.
As with all other Nike Hercules sites, HM-40 was built with a total of five radars. The most noticeable was the high powered acquisition radar(HIPAR) which had a geodesic fiberglass dome covering the actual radar antennae and had a range of over 150 miles. Nearby was the low power acquisition radar (LOPAR), which was primarily used as a backup but helped in the way of accuracy, as target location should be the same on both the HIPAR and LOPAR. By the 1960s, electronic jamming became a concern and the LOPAR’s different frequency was an advantage as both radars would have to be jammed. The other three radars were the Target Ranging Radar, the Target Tracking Radar, and the Missile Tracking Radar.
The site was decommissioned in 1979 and the U.S. Fish and Wildlife Service assumed ownership from the Army to create the Crocodile Lake National Wildlife Refuge in 1980. The refuge was established to protect critical breeding and nesting habitat for the endangered American crocodile and other wildlife, and included the demolition and removal of the launch area. The future of the IFC site remains uncertain.