Serbs, after Clinton's war on them and endless US meddling since, have a right to be upset at more US intervention. But violence against the US embassy is not only wrong, it will backfire. Instead, why not call for the independence of US colonies like Iraq, Vermont, and Puerto Rico?
UPDATE from Daniel: "This is priceless, though. The height of chutzpah: 'I am outraged by the mob attack against the US embassy in Belgrade,' Zalmay Khalilzad told reporters, adding he would seek condemnation by the UN Security Council. 'The embassy is sovereign US territory. The government of Serbia has a responsibility under international law to protect diplomatic facilities, particularly embassies.'"
Daniel, you are right; the US is never short of chutzpah. It felt free to bomb Belgrade, of course, and the Chinese embassy too, in its war of aggression against Serbia. But then, international law is only for non-hegemonistas.