Originally Posted by
Ehrmantraut
Depending on the airline you should have no pasport control and no security as you can go to connecting flights and just go to the gate.
It's not the airline that determines that, so much as it is the origin of the flight.
However, for UK to US connections, there is no security and no passport check (with the exception of temporary/exceptional spot checks, an unlikely possibility but one that may be introduced as needed and without advance notice)