Complex sentence: MANPADS were originally developed in the late 1950s to provide military ground forces protection from enemy aircraft, are receiving a great deal of attention as potential terrorist weapons that might be used against commercial airliners.
Split into simpler sentences: MANPADS were originally developed in the late 1950s to provide military ground forces protection from enemy aircraft. They are receiving a great deal of attention as potential terrorist weapons that might be used against commercial airliners.