Complex sentence: Its service in the nuclear strike role to replace the A- 3 Skywarrior was very short, however, as the RA-5C, it saw extensive service during the Vietnam War in the tactical strike reconnaissance role.
Split into simpler sentences: Its service in the nuclear strike role to replace the A- 3 Skywarrior was very short. As the RA-5C, it saw extensive service during the Vietnam War in the reconnaissance role.