What was the name of the U.S. military operation marking the formal end to combat operations in Iraq?

The operation that marked the formal end to combat operations in Iraq is named Operation New Dawn. This operation officially transitioned the role of U.S. forces from combat operations to advising and assisting Iraqi security forces, which began in September 2010 and concluded in December 2011.

Operation New Dawn represented a significant shift in U.S. military engagement in Iraq, aimed at reducing the military footprint in the country while still providing necessary support to ensure stability. This transition was crucial as it acknowledged the changing political and military landscape in Iraq and the progress that had been made in terms of Iraqi self-governance and security.

In contrast, other operations mentioned in the choices serve different purposes or occurred during different contexts. Operation Freedom's Sentinel focuses on counterterrorism efforts in Afghanistan and other regions, Operation Inherent Resolve is centered on efforts against ISIS, and Operation Odyssey Dawn was a military intervention related to the Libyan Civil War. Each of these operations has distinct objectives and timelines, further reinforcing why Operation New Dawn specifically signifies the end of combat operations in Iraq.