Complex sentence: The Aleppo offensive (September 2016) is the military operation launched in Aleppo in late September 2016 by the Syrian Army aiming to capture all of the remaining rebel-held parts of the city of Aleppo.
Split into simpler sentences: The Aleppo offensive (September 2016) refers to a military operation launched in Aleppo in late September 2016, by the Syrian Army. The aim of the offensive is to capture all of the remaining rebel-held parts of the city of Aleppo.