text:  And what are you hearing from experts about a fail of that level? Some say it's pretty clear this was human error, and it comes down to the placement of security around the rally. Here's one of those experts, former Deputy Assistant Director for the Secret Service Bill Pickle. I think it's human error more than it is perimeter. Perimeter really, to me, is just avoiding the fact that there was not sufficient coverage or resources to stop that from happening.