That said, I think people need to recognize that in many aspects what's happening is connected to societal issues that gun control and gun regulations will have very little impact on - remember, even in Japan somebody could make some kind of battery ignited home-made shotgun and kill Shinzo Abe.
Countries with strict gun control enjoy far lower rates of firearm accidents, suicides, and murders. IMO it's clearly worth the tradeoff. Very few of us live in a place where only guns can solve our problems.
The fact that occasionally someone goes to great lengths to kill doesn't mean we should make it easier for everyone.
The US populace is vastly larger and better armed and capable than Afghanistan.
The US military requires a massive economy to function. If it tries to attack itself, those little armed people could stop it, the economy would crash, and the US military would crumble without needed support and supplies.
A final issue is the US troops would lose a lot of soldiers if they were told to go attack fellow citizens. The soldiers would quit, would hesitate, would not want to kill people they view as their own people.
So armed citizenry absolutely have major power against the govt.
Finally, if you were in a country where the govt set out to kill its citizens, would you rather have arms or be completely unarmed?
We had no military objective in Afghanistan.
Our only goal there was to enrich contractors who had stockholders working at the highest levels in the Pentagon and White House. That goal was achieved spectacularly.