I hate to be cruel, but there is a *reason* that Serbia, which was bombed by France/Germany/U.S./UK in 1999 without UN approval, is not complaining to every Western reporter with a pen, a laptop, or a TV camera about the "double-standard" for bombing Iraq today, and more than likely that reason died with the assassins' bullets today...
Ergo, almost certainly the hit was performed by those angered by the silent double-standard (i.e. Milosovic's loyalists).