Originally Posted by
wariobahn
I wasn't aware this was such a big issue to be honest. I've been to the US many times and never had an issue.
I was stopped at EWR getting off a Dublin flight, and taken for an "interview". Turned out my sin was starting the journey from Ireland on a UK passport. Whatever software or eyeball the US border security people used had flagged me for attention. I'd made similar trips to the US starting at non-UK airports before, and I've made them since, no more problems entering the US but I'm occasionally questioned closely at the check-in security.
So I'd have thought middle-east origin, (what will appear as) evasion of normal check-in procedures, transfer at Istanbul: stands a very good chance of close scrutiny. Perhaps whatever is driving the odd itinerary counters the risk, but only you know the answer to that.