 15th Marine Expeditionary Unit Concludes Support to Operation Inherent Resolve Saturday, April 3, 2021. Indian Ocean, 15th Marine Expeditionary Unit, MIL, embarked on the Mackinac Island Amphibious Group, ARG, concluded operations in support of Operation Inherent Resolve, OYER, March 18. US Marine Corps, F-35B Lightning II Joint Strike Fighters with Marine Medium-Tilt Rotor Squadron 164, reinforced, 15th Marine Expeditionary Unit, conducted a total of nine Operation Inherent Resolve missions as part of Border Counterterrorism operations in the Central Command Area of Responsibility. During the missions, the fighter aircraft departed from the amphibious assault ship USS Mackinac Island, LHD-8, and conducted long-range strikes and counter-OYER missions in Iraq and Syria. Executing missions in and outside the Arabian Gulf shows just how versatile and lethal the F-35B platform really is, said Lieutenant Colonel Christopher Kelly, VMM-164, RAIN, Executive Officer. Embarked aboard the Mackinac Island ARG, our support to the OYER mission shows the depth and responsiveness of the MOE as a maritime force, one that can be called upon when needed. Amphibious groups with Embarked Marine Expeditionary Units provide combatant commanders with a responsive, flexible and forward-deployed asset capable of maritime power projection, contingency operations and crisis response, shaping the operational environment to protect the United States and allied interests in any threat environment. The Mackinac Island ARG and Embarked 15th Marine Expeditionary Unit have been deployed since January in the US Fifth Fleet Area of Operations, OE, supporting security and stability in cooperation with regional and coalition partners. The Fifth Fleet OE encompasses about 2.5 million square miles of water area and includes the Arabian Gulf, Sea of Amman, Red Sea and parts of the Indian Ocean. The expanse is comprised of 20 countries and includes three choke points, critical to the free flow of global commerce.