We don't need assault weapons or other types of scary guns to protect us from a tyrannical government.
Evil things such as concentration camps only happen in other countries, not the U.S. The worst we ever had in this country were reservations and Japanese internment camps where not nearly as many people were killed. Most of them had it coming anyway. They resisted arrest.
Numerous barbaric medical experiments such as those that occurred during the holocaust only occur in other more inhumane societies. That whole Tuskegee syphilis experiment only affected poor uneducated blacks anyway.
Random warrantless searches and seizures of property only occur in military or Communist States. In this country it takes a bone fide national emergency such as Katrina before the U.S. government will forego your constitutional rights and forcibly seize your property to remove your ability to protect yourself.
Government death sentences without trial only occur in truly tyrannical states such as Iran or North Korea. Sure we have the NDAA that gives the president the ability to kill American citizens without trial, but to the best of our knowledge the executions have always been carried out on foreign soil and those guys were bad and very guilty. How do we know they were guilty? Because, the government told us they were, of course.
Genocide and ethnic cleansing only occur in war-torn countries such as Bosnia and Rwanda; yes there was that whole Mormon extermination order, but not that many Mormons were actually killed after they were driven from their homes and forced into Illinois. Sure they were attacked and forced to leave there too, but only a few thousand of them died as they were forced to travel across the country. All in all, it only took about 150 years before the Missouri governor rescinded the extermination order, so in hindsight it was a self-correcting issue. Besides, have you been to Salt Lake City? It's beautiful!
But the U.S. government has far more sophisticated weapons and could easily crush any civilian militia group only equipped with rifles anyway. We would need tanks, or Apache helicopters for this opposition to be effective. Realistically the Afghan fighters - oops, I meant American civilian militia groups - would be crushed and the war or resistance movement would be over in a few days at most - OK, maybe a week tops.