In my introductory comments I talked about a large number, but in the past year, for example, we've had 48 suspended transportation security clearances as a result of the perpetual vetting checks that are done. We've had 20 cancelled, and we've had 448 that were refused, either due to adverse information that was deemed to be significant, or to a lack of information because we can't check their history. So yes, that happens.
On May 11th, 2017. See this statement in context.