Complex sentence: The'Leonidas-2' development involved extensive modification of the previous model, done by ELVO itself in 1987 with the aim to essentially develop it as an Armored Infantry Fighting Vehicle (AIFV).
Split into simpler sentences: The'Leonidas-2' development involved extensive modification of the previous model. This was done by ELVOin 1987 with the aim to essentially develop it as an armoured infantry fighting vehicle (AIFV).