Operation Inherent Resolve (OIR) is the U.S. military's operational name for the international military intervention against the Islamic State (IS),including both a campaign in Iraq and a campaign in Syria, with a closely-related campaign in Libya. Through 18 September 2018, the U.S. Army's III Armored Corps was responsible for Combined Joint Task Force – Operation Inherent Resolve (CJTF—OIR) and were replaced by the XVIII Airborne Corps