Complex sentence: Between 1952 and 1961, provided air defense for Iceland, operated Keflavik Airport, and furnished base support for all U.S. military forces in Iceland participating in its defense under the North Atlantic Treaty Organization (NATO).
Split into simpler sentences: Between 1952 and 1961, provided air defense for Iceland, operated Keflavik Airport, and furnished base support for all U.S. military forces in Iceland. Performed its defense mission under the North Atlantic Treaty Organization (NATO).