Complex sentence: In 1966, some members of the KTA, led by H. H. Choi, formed the International Taekwon-Do Federation (ITF); other members founded Kukkiwon and the World Taekwondo Federation (WTF) in the early 1970s.
Split into simpler sentences: In 1966, some members of the KTA, led by H. H. Choi, broke off from the KTA and formed the International Taekwon-Do Federation (ITF). The Kukkiwon and the World Taekwondo Federation (WTF) were created by the KTA in the early 1970s.