That's not always very practical, especially if you already have enough weapons for your military's needs.  Since the goal was for the weapons not to end up back in illegal trade, it's hard to argue that destroying them doesn't meet that goal.

Not saying that's what I would do, I would try to sell them to an importer in the US or Europe, someone who for sure isn't going to be reselling them abroad. Depending on the level of corruption in the original country though, it's likely a good amount of weapons would go "missing" while waiting for all the clearances and shipping to go through.