Complex sentence: The extension program was intended to keep the Draken flying into the 2000s, but due to cutbacks and high maintenance costs, the Draken was phased out of Swedish service in December 1998, although the aircraft remained in limited numbers in both military and civilian roles.
Split into simpler sentences: The extension program was intended to keep the Draken flying into the 2000s, but due to cutbacks and high maintenance costs, the Draken was eventually phased out of service. The Swedish Drakens were officially retired in December 1998, although the aircraft remained in limited numbers in both military and civilian roles.