The primary goal of the US Military - other than “Kill People and Break Stuff” - is to defend the United States in military conflict. Typically, this is only necessary when the United States is actually at an official state of war, as declared by Congress.
At present, it is extremely easy to send US troops to places where they do not need to be for questionable reasons.
As a means of decreasing unnecessary US military activity, the United States should overhaul the current system that the US army operates. Rather than a large national US Army, the Army would instead primarily consist of National Guard and militia forces that are based on a state-by-state level. The national army would be minimized in size, while the State National Guard and Militias would be increased to compensate.
The US Army wouldn’t be disbanded entirely, but it would mostly consist of a small number of officers (mostly Generals) who exist to coordinate between the State forces and provide national-level leadership in case of actual war.
Unless the United States is actually attacked, or war is officially declared, it would be far more difficult to deploy the US Army for unnecessary military operations.
In circumstances where there is still a genuine need for the US to deploy its military muscle in emergency circumstances, the other US military branches - Navy, Marines, Air Force, Coast Guard, Space Force - would maintain the same core organizational structure.