This is one case where I enjoy the fact that most of my international travel is on official orders, which clearly state that I am not allowed to discuss the business of said travel. Any government official that asks me what I am doing (had a CBP officer ask me in the jetway on one of my flights to NRT last year) gets the orders page shown to them. If they continue, I advise them to contact my security office, as I am not allowed to discuss the issue further.