Yep, profiling it is, here is how it works in the US:
a)Alien ( this is American for a non US citizen ) , considered a 80% terrorist => you get one S on your profile
b) Booking an airline ticket through internet,giving a non US adress alarm starts ringing
=> you get a second S on your profile
c)Paying with a non US credit card = > you get your third S in your profile
d)booking a one way trip => you get your SSSS on your boarding pass and are elevated to " special treatment " when you get to security, prolonging the "intensive search " by .5 - 1hour
Good thing you meet a lot of fellow Europeans whilst waiting in line who are all treated the same way. The only Americans you meet are the intelligent TSA people who are searching though your dirty underwear.
When I book through a US company credit card with my US driver licence, SSSS boarding passes never happen.
US citizen good guy = European citizen bad guy
Frank