Just start night bombing the Donetsk forces or whatever they're calling themselves within Ukrainian borders and just deny, deny, deny the whole thing like they're doing with this aircraft. Invent some separatist group to blame it on, who cares? The US intelligence community surely knows exactly where they are. There is no reason in the world for this to be tolerated.
Don't even have to involve Russia. After all, we've heard for months that Russia has nothing to do with the Ukraine separatists. It's all homegrown anger toward Kiev, etc.