While we can consider Juba a reliable ally for now, we don't know what will happen in the future. If there's one lesson we can learn from US engagement in Africa over the past fifty years, it's that putting more weapons into a situation always backfires against us, and, more importantly, against innocent civilians in the region. South Sudan is a prime example of this problem; go to a weapons dealer and you'll find US and Soviet-made weapons shipped into Somalia and Ethiopia during the Ogaden War, or perhaps a Kalishnakov that's made its way from Angola where it was used to fight South Africans before playing a role in the Congo wars. Or you could check the tank dumps outside Asmara and Addis Ababa, where larger weaponry sit in their graves after terrorizing countless civilians. The problem with giving weapons to South Sudan is that we can't guarantee how those weapons will be used over the short or the long term.