Rumors of a coup began circulating in late summer of 1963. The United States endeavored to make clear its opposition to such action—even dispatching a high-ranking officer from the United States Southern Command in the Panama Canal Zone to try to convince the chief of the armed forces, Air Force Colonel Oswaldo López Arellano, to call off the coup. Villeda Morales also tried to calm military fears, taking the carbines away from the Civil Guard and opposing plans for a constitutional amendment to restore direct command of the military to the president. All these efforts failed.