The U.S. has supported secession in the past, when it serves U.S. interests. From Vladimir Golstein at consortiumnews.com:
The U.S. has declared that Donbass is different. How it is different, nobody will say, because you are not supposed to ask, writes Vladimir Golstein.
There once was a country called Yugoslavia. It was a multi-ethnic, multi-religious federalist country, rather prosperous by Socialist standards, and consisting of proud people who stood up to Adolph Hitler and even Joseph Stalin.
There were intermarriages, great food, and great films too. And then the West — once the Soviet Union began to collapse — decided that it was Yugoslavia’s time to collapse too. It would no longer be a country but the land of ancient Balkan hatreds. And they began to foment them and foment them, blaming one republic in particular: Serbia.
Serbian villains were blamed for slowing the rapid European integration of all the other republics, which began to declare their independence. This independence — Slovenia, Croatia and so on — was quickly embraced by the West. Germans were there first, trying out their new role as the masters of Europe, so all these republics were eventually recognized and then — since the population was mixed — civil strive began within each newly, independent republic.
Serbian minorities from every republic began to be harassed and kicked out. All this was condoned and supported by the West, which started a new narrative: great separatists, bad Serbians. [The Clinton administration, including then U.N. ambassador Madeleine Albright, gave a green light to Croatia to ethnically cleanse a quarter of a million Serbs from the Krajina region. Years later, angry Czechs in solidarity with Serbs, confronted Albright at a book signing in Prague. She called them “disgusting Serbs.”]
Those who remember, can recall wars, and bombing and propaganda campaigns. In 1999, NATO intervened militarily to help the largely ethnic Albanian Kosovo gain its independence from Serbia. The autonomous province of Kosovo had voted 99 percent in favor of independence in a 1991 referendum. Eight years later NATO was bombing Belgrade on its behalf.