My simple policy proposal is to deny the military the right to deploy combat troups in the absence of a Congressional Declaration of War. The last declarations of war were made during World War II.
Because Congress is infamous for avoiding responsibility for anything, the number of foreign wars would instantly drop to zero which would be a good thing.
The Department of Defense (formerly and more accurately known as the War Department) is the largest employer in the United States: 1.3 million on active duty, 742,000 civilian employees, 826, 000 National Guard and Reserves, 2 million retirees and their families, and who knows how many contractors. The DoD web site claims more that 3 million employees. The current budget is $524 billion. Assuming a 2017 Federal budget of $4 trillion, defense is about 13% of the total. Some web sites add in Veteran’s benefits and foreign aid thus increasing the “defense” budget to $880 billion. Calculated in this fashion, “defense” spending is over 20% of the Federal budget.
To be anti-war is to take on the largest economic interests in the United States. President Dwight D. Eisenhower on January 17, 1961, during his farewell address coined the term the military-industrial complex (MIC). Please note that President Eisenhower did not warn of the MIC until he could not longer do anything about it. Today, with the addition of the Surveillance State as a new cancer upon the body politic and we might need a new acronym MIC-SS standing for the military-industrial complex-surveillance state.
National defense is one of the only three legitimate functions of a proper, moral government in Libertarian theory. So some form of DoD would survive a totally Libertarian government. You can be sure, though, that the size of DoD would be a tiny fraction of its present self. We are talking about a one hundred years process of reduction, though.