Complex sentence: In April 2006, the Third Army Central Coalition Forces Land Component Command (CLFCC) assumed responsibility of the 1st Corps Support Command (1st COSCOM) from the XVIII Airborne Corps and re-designated it as the 1st Sustainment Command (Theater).
Split into simpler sentences: In April 2006, the US Third Army, in it's role as Central Command's Coalition Forces Land Component Command (CFLCC) assumed command of the 1st Corps Support Command (1st COSCOM) from the XVIII Airborne Corps. Under US Army reorganization, the 1st COSCOM has been re-designated as the 1st Sustainment Command (Theater).