I think referring to the oppression of black people in the USA as "white supremacy" is a very dangerous thing to do as it perpetuates the "them and us" thinking that is at the heart of the problem and reinforces prejudice in those who feel assaulted by such terminology. Colour is an accidental part of the problem. It is more to do with the same thinking that gives rise to the caste system in Hinduism. Remember, slavery in the USA arose initialy from the need of aristocrats exiled from England to Virginia, following the execution of Charles I, to replace the feudal serfs they left behind. Also bear in mind that the enslavement of European people in the Ottoman Empire was just as big an obscenity as the enslavement of African people in the Americas. In other words, it is the down to the age old tendency of the powerful (whoever they are in any particular situation) to oppress the relatively powerless and, in doing so, coming to view those they are oppressing as inferior to the point of not being fully human. That powerless white people in the United States buy into this thinking is probably still down to their fear of becomming the powerless again (they are the descendants of European peasantry). Therefore, we should be bringing people together in the language we use rather than using language that reinforces division, even if the divisive language appears, on the surface, to be an accurate description of "where we are today."