Agent Orange was dropped by the US to poison a foreign population.
In Iraq and the former Yugoslavia, depleted uranium was used.
In Western countries,
things are a bit more complicated
because various states have tended to avoid using direct forms of physical violence to quell their own populations
( unless you belong to some marginalized group or hit a raw nerve,
as did the Occupy Movement last year ).
The pretence of democracy and individual rights has to be maintained.
One option has been to use South American crack cocaine or Afghan heroin
to dope up potential troublesome sections of the population.
It’s worked wonders:
highly lucrative for the drug running intelligence agencies and banks awash with drug money (1),
while at the same time serving to dampen political dissent in the most economically and socially deprived areas.
Another tactic has of course been the massive ever-increasing growth of the surveillance industry to monitor ordinary citizens.
But drugs, surveillance and direct violence
are kind of a last resort to keep a population in check.