In the latter part of World War II the fighter-bomber began to take over many attack roles, a transition that continued in the post-war era. Jet-powered examples were relatively rare but not unknown, such as the Blackburn Buccaneer. The U.S. Navy continued to introduce new aircraft in their A-series, but these were mostly similar to light and medium bombers. The need for a separate attack aircraft category was greatly diminished by the introduction of precision-guided munitions which allowed almost any aircraft to carry out this role while remaining safe at high altitude. Attack helicopters also have overtaken many remaining roles that could only be carried out at lower altitudes.