Which of the following indicates a COA is not acceptable?

A course of action (COA) is determined to be unacceptable when it poses an unacceptably high risk of civilian casualties. This is critical in military operations where adhering to the principles of international humanitarian law and protecting non-combatants is paramount. High civilian casualties can lead to significant political, social, and moral repercussions, damaging support for military operations and undermining mission objectives.

In the context of joint air operations, the consideration of the risk to civilian lives can dictate not just the immediate tactical decisions, but also long-term strategic implications. A COA that contributes to excessive civilian harm will likely be seen as failing to meet ethical, legal, and operational standards. This highlights the importance of balancing military objectives with humanitarian concerns.

The other factors, such as adherence to budget constraints, achievement of strategic objectives, and resource effectiveness, do not alone determine a COA's acceptability. While these aspects are important for operational planning, they do not outweigh the necessity of protecting civilian lives. Therefore, the presence of high risks to civilian lives unequivocally marks a COA as unacceptable.