Complex sentence: Army Air Force Headquarters in Washington, D.C. looked into the matter in mid- 1943 and concluded that there were only 16 ships involved, but GHQ SWPA elected to stick to its original story.
Split into simpler sentences: Army Air Force Headquarters in Washington, D.C. looked into the matter in mid- 1943 and concluded that there were only 16 ships involved. However, GHQ SWPA elected to stick to its original story.