Hart was born Howard Lester Phillips Jr. on 16 October 1940 in St. Louis, Missouri, the only son of Eleanor Laidley and Howard Lester Phillips. Within months of his birth the family traveled to Manila, Philippines where Howard Sr. was an engineer with a U.S. firm. When the Japanese invaded Manila early in World War II, the family was interned first at the University of Santo Tomas in Manila, then moved to Los Banos. On 26 February 1945, The 11th Airborne Division jumped in behind Japanese lines and extricated the 2000+ internees under fire. They took them to Manila and onward to the United States.