Here's what The Washington Post wrote about the impact of defense cuts in an editorial on the topic:
Since 2010, defense spending has been slashed 21 percent in real terms, according to the Center for Strategic and Budgetary Assessments , which also produced last week’s war cost study. The Army has announced plans to reduce its size to the lowest level since before World War II, while the Navy is on its way to the smallest number of ships in a century...
The undeniable reality, as a bipartisan commission created by Congress recently concluded, is that the 2011 budget plan was a “serious strategic misstep” that has hamstrung the Pentagon’s ability to respond to the multiple international crises of this year.
Paying for wars against the Islamic State, Ebola and more - The Washington Post
The newspaper went on to urge restored funding. In a world in which one assumes that American power makes a positive contribution to stability and in which the U.S. has many far-flung interests and strategic allies, by a situation in which the Army would be at its smallest level since before World War II and the Navy would have the fewest ships in a century.
President Reagan was fond of arguing for "peace through strength." He wasn't articulating a doctrine of crusading military intervention. Instead, he was arguing that strength was a necessary component of deterrence. If successful, deterrence would reduce the number of conflicts in which the U.S. would have to get involved. Without strength, deterrence would fail.
IMO, the conservatism of President Reagan was premised in a sound understanding of history and the world. The Paul variant, which would reduce the military well beyond the figures cited in The Washington Post's editorial is something quite different that is based on idealistic assumptions of a peaceful world and dependence on others' good will.