 The United States' involvement in the war in South Vietnam as well as in Laos and Cambodia was an attempt to stop Communist aggression and keep Southeast Asia free. It was a commitment made by four United States presidents through from a small force of American advisory personnel to one of over a half million Army, Navy, Marine and Air Force participants. In 1965, as the American military buildup accelerated, the Communist Viet Cong and North Vietnamese armies escalated the war in an attempt to cut South Vietnam in half. They increased their hit-and-run guerrillas' tactics against Allied forces and Republic of South Vietnam installations and adopted a tactic of stand up and fight with battalion-sized forces. But this tactic made the communists more vulnerable to air power. The decision was made to intensify the use of aircraft in the Vietnam action. The rapid buildup brought additional Air Force personnel to Southeast Asia. The teamwork displayed by this group of combat crewmen and ground personnel, often while under enemy attack, was a significant phase in Air Force history. In January 1973, a ceasefire went into effect and the return of U.S. prisoners of war began immediately. It was checkout time at the Hanoi Hilton as the prisoner of war camp in Hanoi had become known to its inmates. American prisoners began their long trip home. However, bombing continued in Laos and Cambodia until August 1973, thus ending almost 12 years of Air Force involvement in Southeast Asia. In addition to its combat role, the Air Force participates in many non-combat activities that are historically important. Many of these came about because of the social, economic, and environmental changes to our society during the 60s. Military civic action, for example, includes projects useful to the local population in such fields as education, training, public works, agriculture, transportation, communications, health, sanitation, and others that contribute to economic and social development. One of the most serious obstacles to progress in developing nations is the lack of roads and transportation. The Air Force has airlifted equipment, necessary supplies, material, and food to remote areas. Timely medical attention was made available to stricken people deep in the jungle. Such civic action offers a way for military forces to identify what the nation's civilian needs. Local Air Force commanders are encouraged to become involved in community affairs as part of the Air Force Community Services Program. Such action is not limited to war-torn nations. When disaster strikes anywhere in the world, it often signals immediate extension of Air Force human and physical resources. Food, clothing, water, medical supplies, and technical assistance are quickly airlifted to the stricken populace. All local Air Force units and personnel are authorized and encouraged to volunteer their services. Humanitarian assistance is an important part of the Air Force mission. Pollution is also a problem that concerns the Air Force. To reduce air pollution, current aircraft engines are being modified to reduce polluting emissions. Looking to the future, the new F-15 aircraft uses the first aircraft engines specifically designed as non-smokers. Ecology has long been a part of Air Force operations. Generally, Air Force installations have land which must be maintained as a safety buffer, but which is not needed for facilities. This land has been used as sanctuaries and preserves for patient wildlife resources since 1958. Discrimination of any kind is counter to Air Force policy, and concentrated effort is expended to dispel prejudice and mistrust wherever it may exist. At all command levels, formal training through education programs is mandatory. The goal is to eliminate discrimination in all its manifestations. Solving problems together is imperative in a highly technical Air Force. As a result, a premium is placed on education. Consequently, the Air Force is a primary producer of highly skilled specialists. Nearly half a million specialists annually take service or service sponsored education courses, such as those of the Air Training Command, or the Air Force Institute of Technology. Many participate in the Community College of the Air Force program, which gives them college credit for in-service education and training. Air Training Command Field Training goes to the student. There is benefit from correspondence courses. A large number of Airmen study at technical training centers. Many of the skills learned are directly applicable to civilian industry. National civilian productivity gains much from contributions of Air Force trained professionals and technicians. Conversely, the Air Force gains from the skills of civilian industry, for its defense products are the finest in the world. Excellent examples are today's advanced jet aircraft. The SR-71 reconnaissance aircraft provides the Air Force with an expanded global view. Its speed and range were demonstrated in September 1974, when it flew from New York to London, England in 1 hour and 56 minutes, a distance of 3,490 miles at 30 miles a minute. The transatlantic flight shattered the existing speed record of 4 hours and 45 minutes, with a top speed which exceeded 3 times the speed of sound at 80,000 feet altitude. Its return flight from London to Los Angeles, California, took only 3 hours and 42 minutes. In July 1976, the SR-71 broke 6 speed and altitude records previously held by MiG-25 and U.S. Air Force YF-12A aircraft. The new records include speed over a 1,000 kilometer closed course and over a 15 to 25 kilometer straight course. It also set an altitude mark of 85,126 feet for sustained flight. More aviation history was made over a period of 17 days in January 1975. During Operation Street Eagle, the F-15 Eagle broke every existing climbing record in aviation history. It completed the record sweep when from Grand Forks Air Force Base, North Dakota, it took off and climbed to 30,000 meters, approximately 103,000 feet altitude in just 207.6 seconds. This performance exceeded the best previous 30,000 meter climb by 35.8 seconds. The mission, as part of the rugged F-15 flight test program, provided new data on high altitude capabilities of the aircraft and its pilots. Also, it was a clear demonstration of American technology. The high performance, highly maneuverable F-16 multipurpose fighter is expected to outperform any known enemy threat in its class in the foreseeable future. The formidable B-1 bomber is much advanced over the aging B-52. It is capable of greater speed, heavier payload, and a better capability to penetrate enemy defenses. The A-10, designed to support frontline ground troops, can carry a heavy load, remain airborne for long periods, and take off and land on short runways. As for the future, the Air Force uses its previous X-15 space experience to move toward new frontiers. Working with the National Aeronautics and Space Administration, the Air Force investigated the possibilities of using X-24 research vehicles in the study of future hypersonic flight, which is above 3,500 miles per hour. Experience gained with the X-24 has contributed to development of the new space shuttle concept. Called the Enterprise, this orbiting vehicle will be used by the Air Force for Department of Defense space missions. After its flight in space, the Enterprise will re-enter the atmosphere and fly like an airplane to a designated landing area. The United States Air Force, on the threshold of the future, provides the American people with a capable and flexible aeron dedicated to the preservation of world peace.