Please tell me, why I need to go through security again after I landed from a foreign country and continue on a U.S. domestic flight, let alone another International flight?. I figure, I get checked at origin, nothing happened on the flight, I arrive in Canada or ( for argument sake ) in DTW, LAX or DFW. I have to go through Immigration, pick up my luggage, which was already checked and then go through customs. Then I have to recheck my carry-on luggage but one more time have to take my belt and shoes off, take the laptop out of the bag, do the whole stupid thing, wasting valuable time. For what? OK, I might have gotten a bottle of water on the flight, all of a sudden that bottle of water became a dangerous object? Still. Maybe I am stupid ( happens at my age ) but what did I possibly pick up during the flight that all of a sudden presents a threat to the U.S. And why do I have to present a boarding pass to prove on what flight I am on, if I have to enter a non-sterile area like at DFW, ORD or LAX ( where so many times one has to change terminals )? This is just nuts, but we already know this. There really is a lot of frustration out there. It really is!!!