Originally Posted by
nighthawk117
I dont see how this is an issue - you dont clear security when you arrive in the US - you clear customs. Passengers travelling UK-US already mix, and it isnt a security issue now.
At the DUB facility, US-bound passengers clear a TSA security check before they go through the US immigration check. Passengers having cleared both are kept separate from those who have cleared just the security for non-US passengers.