I don't assume the US (merely using it as an example when we question the possibility of conspiracy theories being true).

Arafat could have been killed by other (more radical) Muslims, by the Israelis, by any number of people (though the method suggests a government was probably involved). Milosevic was likely killed by some western government, based on circumstance (being in custody at the Hague), and the fact that he revealed that people were trying to kill him before it happened...