Complex sentence: In reality, the assaults were carried out by terrorists from the Abu Nidal Organization (ANO) in retaliation for Operation Wooden Leg, the Israeli bombing of PLO headquarters in Tunis on October 1.
Split into simpler sentences: In reality, the assaults were carried out by terrorists from the Abu Nidal Organization (ANO). They claimed to be retaliating for Operation Wooden Leg, the Israeli bombing of PLO headquarters in Tunis on October 1.