Deeply in debt, the US must dramatically reduce military spending. George Washington correctly warned against permanent military alliances, and many founding fathers were strongly opposed to a large standing army, both because of the cost and that it could be used for domestic political oppression. There is no chance that the USA will be invaded, as it is blessed with two large oceans and two weak neighbors, and a heavily armed populace. Further, a large standing army entices politicians to support unnecessary foreign adventures. Therefore, the US should withdraw from NATO, withdraw most military forces from outside of the US, convert most of the US Army to reserve forces, and reduce the size of the navy’s surface fleet. President Trump can sell this in part by highlighting that it would reduce his ability to act as a domestic tyrant.
The US can retain numerous active-duty Marine expeditionary units and Army Rangers companies for rapid deployment, maintain the special forces for covert actions and training with foreign forces, and a reduced navy. In this case, the primary US offensive and defense forces would be USAF, USSF, and the nuclear submarine fleet, and any large-scale foreign war would require a massive call-up of reserve forces, which is itself a major check on political overreach.
The US should create new military alliances with individual countries on a case-by-case basis, such as those needed to secure access to forward air bases (Diego Garcia, Aviano, Kadena), with Canada for the northern early warning system, and to support South Korea. These alliances must require periodic renewal by congress and the president. Other alliances can be formed as needed, say with Poland or the Baltic states, but none can be permanent.
This would clearly be a painful process, especially for conservatives like us who strongly support the military, but it cannot be avoided due to the massive US debt and the weakness of men.