The Constitution left law enforcement up to the people. Policing in the early United States was restrained to elected sheriffs.
Sheriffs only is a good idea.
It might be too late, though.
Internationally, the military should handle our enemies, and for those who injure us we should have a policy of massive retaliation/destruction.
Knock down the WTC, and we fire bomb one of your leading cities with no effort to build a democracy, to rebuild your country, or even to occupy you. The glorious leader’s residence becomes a holocaust and lights up the night.