The Afghans could teach us a lot about how to deal with our own "Central Govt" , Ignore them and they will go away

The answer is actually fairly simple, to brutal and realistic for OUR gutless politicians, but simple.
Bring all non training Army troops home, put them on the border with orders to shoot to kill
Leave the Spec Ops forces to search for and destroy the various terrorist groups.
Continue Navy / Marine Cruises around the world to look after American interests as they were intended and have done since 1798
If a country pisses us off, use missiles, Air force, Navy, and Marine air craft to target their bridges, power supplies, food supplies, leadership, and industrial base. In the modern world this is the equivalent of what Rome did to Carthage. Leave their women weeping and their children starving, only because we no longer sell captured populations into slavery.
Countries like Iran, N Korea and Pakistan should have their nuke facilities hit with Nuke bunker busters, we' designed them in 91 for Iraq and never used them 1/2 KT and they generate VERY minimal radiation or fallout, it's all contained inside the bunker.