Complex sentence: The Southern Yemen offensive is an ongoing campaign against the internationally recognized Yemeni government of Abd Rabbuh Mansur Hadi in Aden, which is being carried out by Houthi forces and forces loyal to the former president Ali Abdullah Saleh.
Split into simpler sentences: The Southern Yemen offensive is an ongoing campaign against the Yemeni government in Aden. It is being carried out by Houthi forces and forces loyal to the former president Ali Abdullah Saleh.