Could it be that the reason Serb soldiers are in Afghanistan is so they can get training in advanced counter-insurgency tactics? From what I've read, there seems to be a gradual (but quiet) increase in American military aid to the new Serbian government.
I think in the final analyst the real reason for a US military base in the Kosovo region will be to provide a strong presence against the radical muslims of Kosovo and other islamic weirdos who are their friends... ie. bin laden's group.
The Serbs haven't made it to Afghanistan yet, in large part due to individuals like Stojanovic, around whom the stench of war crimes in Kosovo lingers too strongly.
Furthermore, his statements are less than creditable in light of the lack of attacks on US forces in the region, as compared to our experience in Afghanistan or Iraq.
Serbia is being coaxed into NATO, via the pfp, but if Mladic isn't turned over come March, we're back at square 1 and Serbia will be back out in the cold as far as economic and military relations with the US go.