Acting on the recommendations of the Joint Study Group, Defense Secretary Robert S. McNamara advised the Joint Chiefs of Staff (JCS) of his decision to establish the DIA in February 1961. He ordered them to develop a plan that would integrate all the military intelligence of the DoD, a move that met strong resistance from the service intelligence units, whose commanders viewed DIA as undesirable encroachment on their turf. Despite this resistance, during the spring and summer of 1961, as Cold War tensions flared over the Berlin Wall, Air Force Lieutenant General Joseph Carroll took the lead in planning and organizing this new agency. The JCS published Directive 5105.21, "Defense Intelligence Agency" on August 1, and DIA began operations with a handful of employees in borrowed office space on October 1, 1961.