It's become politically unacceptable for any African-American men to be killed by police. Given that the US is a violent country with a lot of guns and aggressive police, and African-Americans are a marginalized, systemically disadvantaged underclass, this is a recipe to bring a racially divided nation to the brink of civil conflict.

The Dallas attack on police, carried out by a trained soldier, looks right out of a textbook on guerilla war. I think it would be quite easy for organized paramilitary groups to make many US cities ungovernable, particularly with so many veterans around.

The Black Lives Matter movement makes more sense through the lens of other ethnic separatist movements, such as Yugoslavia and Northern Ireland. It might sound shocking, but if they regard any white law enforcement or government as illegitimate, their demands seem to imply separatism and African-American nationalism, in the vein of Marcus Garvey and Malcolm X.