It has been a couple of years, at least, since I've returned to the US from Europe. Recent returns from ME, CA, and SA have all involved additional security for US-bound flights.
Earlier this week, FCO-MUC-IAD. Arrived at MUC K and left for IAD from MUC L. Other than a document check, there was no additional security for US-bound flights. Is this a recent change or additional security is just random?