Very good one!! It seems our entire security force was asleep at the wheel, and/or too inclined to trust and rely on the locals, who were also asleep at the wheel.
I think it was more of a case of a President who over-rode the Secret Service in his rush to go grandstand at the Mandela memorial. That trip was thrown together so quickly there was no possible way the Secret Service could have done any vetting whatsoever, and were likely as not over-ridden on any security concerns they may have raised. Obama and Company just hopped on Air Force One and hauled ass to South Africa against any and all good advice.