[freeasinbeer]

The bare feet mean they are foreign fighters. The story goes, that the local terrorists don't trust the foreign terrorists (i.e. they think they will leave once they get fed and armed by the locals), so they make them trade in their shoes for weapons.

Makes them all the easier to pick-out as well.

[Wolfstar]

I guess, unlike the old saying that there's honor among thieves, there's no honor among Allah's warriors, i.e., terrorists.