Since it began.
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It depends on what the question means by 'an issue'.
It was not an issue in the Holocaust.
Yes
There have been many things like the Holocaust, but none over such a long period, across so many countries and in the West.
morality is a personal issue.
a very long time
Hatred of the Jews which had been prevelant in Europe since long before the Holocaust
Yes, there have been multiple genocides after the Holocaust.
There has been no Australian holocaust.
food was a massive issue, for the victims it was constantly on their minds. logistics was a constant issue and the war was a large issue.
9/11
The physical weapons would have been mainly standard issue, add some clubs and ad hoc weapons.
you can, but whether they read the letters themselves or not is another issue.