Complex sentence: Guided munitions allow more aircraft to perform the close air support mission and has reduced the requirement for a specialized CAS aircraft; since 2001, multirole aircraft and bombers have performed 80 percent of CAS missions.
Split into simpler sentences: Guided munitions allows more aircraft to perform the close air support mission and has reduced the requirement for a specialized CAS aircraft. Since 2001, multirole aircraft and bombers have performed 80 percent of CAS missions.