Complex sentence: The Soviet news agency TASS alleged that Paladin was involved in training US Green Berets for Vietnam missions during the 1960s, but this is considered unlikely, since Skorzeny's methods were considered somewhat antiquated, and he resented the USA for its role in destroying Nazi Germany.
Split into simpler sentences: The Soviet news agency TASS alleged that Paladin was involved in training US Green Berets for Vietnam missions during the 1960s, but this is considered unlikely. This is because Skorzeny's methods were considered somewhat antiquated, and he resented the USA for its role in destroying Nazi Germany.