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...
<ignore reason=probably not true>There aren't many with the capability.</ignore> Polonium has no stable isotopes and is naturally so rare that the nuclear industry synthesises it from bisimuth using neutron beams in specialist nuclear reactors. <ignore reason=probably not true>Also, apart from triggers for nukes and poisoning dissidents, it has very few uses.</ignore>
I don't understand who/what your markup is meant for? Are you claiming that things you're writing are probably not true and should be ignored? Then why are you writing them? This seems a little too clever.
I put the markup in after it was pointed out I was probably talking bollocks there. I didn't want to delete the wrong info as that would make the comment after make no sense, so I did that instead.