Criticizing heads of state, and actual mass murderers, is always appropriate. Mixing that up with racism is just an excuse to have a scapegoat for your own failures. America did one successful genocide already and ran out of Amerindians to point fingers at, so now European traditions like antisemitism are back in vogue, but even if you did the perfect holocaust and ran out of semites to anti-, you'd be back at square one looking for another substitute scapegoat.
How about we skip right to blaming the Irish?