The standard in practice is established in the Nuremberg and Tokyo trials. Rescuing citizens from apparent danger (Grenada, Panama), supporting one faction against another (the USSR in Afghanistan) is not so clear. In Haiti, the American intent was to restore a lawfully-elected government.
As I recall, those trials mentioned wars of aggression a lot. Under that standard, there should be an international intervention in Crimea and Ukraine.
Then again, the USSR wasn't exactly on a pedestal when it came to wars of aggression, and that was remarked upon at the time. The other part of the trials had to do with war crimes & crimes against humanity. Let's just say interventions over those grounds have been...inconsistent...to say the least. There's nothing at all about interventions over ideology, of which there have been many. Using these standards is really not clear-cut at all.
Oh, there's plenty of murderous crimes to relate. The argument comes over whether one holds the view that national sovereignty is absolute. I have observed that no one is really consistent about such a view. Some of the biggest governments that prattle on about this are absolutely guilty of doing the same thing when it's in their self-interest. True about plunder, though - what Saddam Hussein did to Kuwait was a perfect example. Of course it was also a perfect example of a war of aggression, but that didn't stop the Dems from mostly opposing it back then.
For extra credit, class, look up Dem and Rep statements from the Gulf War and the Kosovo War and discover how utterly shallow and partisan most politicians are! Barbara Boxer the warmonger! Tom DeLay the peacenik! Or vice versa! Depends on if the president starting the war is a Democrat or Republican!
Dude. Really. Civil Rights Movement (the opposition to it, silly) - CREEP - McCarthyism - Plot against FDR - Red Scare - Jim Crow - Civil War - Fugitive Slave Act - Trail of Tears - Alien and Sedition Acts - and that's just off the top of my head. Other people would probably add to that*. Some perspective, here.
*Kids these days. If you thought post-9/11 was super-duper bigoted against Muslims, let me recall the 1980s and early 1990s...
I'm seeing wide condemnation of these groups. Well, not so much from Trump, but I don't think he's going to make it through one term, much less two. But to quote the BBC, "The overwhelming majority of Americans are appalled by all that the hideous scenes in Charlottesville represent." So dial down the gloom and doom a bit
