"Sheep" Smugglers

From CNN:

Some local villagers have claimed the people killed in the attack were sheep smugglers. Pentagon officials said they might have been smugglers, but said U.S. intelligence strongly suggests high-level Iraqis, not sheep, were their cargo.

Why do people smuggle sheep? Are sheep illegal in Syria? “Hey, buddy, I’ll give you $100 a head to get these Suffolks across the border…”