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!!!

You can access your hand luggage in the customs hall, so you could pull out a knife or even a gun from your checked bag and then proceed onto your next flight with it-- that is why you go through security again.

Your quesion is better posed in HKG where you don't touch your checked bags if you are a transit passenger . . .

Understood, but I am coming in from HKG, NRT or FRA/AMS. Isn't my checked luggage checked there already? Ooops, I made a bad mistake, I had a drain cleaner in my luggage and they took it out, meaning they do check my luggage. Well, there are always the obvious questions exactly as you posed: he will pull a knife out of checked baggage, maybe a gun. For crying out loud, I am nearly 70 years old; I just want to go home!!! Oh, I forgot, I was wearing loose pants, I am filled with explosives and need a thorough x-ray to check if all my genitals are still there. And then go overboard and look what my beautiful Japanese wife has to show. It is sick, really sick!!!

You are allowed to have knives and guns in your checked baggage. You can access your checked baggage in the customs hall. You are unlikely to have a gun in your checked baggage when while traveling internationally, but you can have a large knife, sword, crowbar, etc. If you are not re-screened, you can carry any of that onto the plane. Is it really that hard to understand? It doesn't matter how old you are or where you are going. Do you think you should be exempted from security procedures because of your age or where you 'just' want to go?

Unfortunately, you are laboring under a few misapprehensions. The fact of the matter is: airport security doesn't have to be effective, it just has to look effective.

Making people go through security twice does look effective now, don't it?

While this is , no doubt, annoying, it is actually one of the screening activities which makes some sense - not just because of the access to luggage as described by others, but some countries' security is even more theater than our own.

its not only the us....when connecting intl-intl at scl, i have to go thru screening....it's the way of the world....

The rules for checked baggage and for carry-on are different.

Guns are legal in checked luggage by US standards. The ammo, also. (Although not in the gun.) Once you've had access to your baggage you could have a loaded gun and of course you have to be rescreened.

If you're coming from someplace that doesn't allow guns you could still have a knife. Perfectly legal basically anywhere (I'm thinking of the things you normally use in the kitchen), fine in checked baggage but not for carry-on.

When I arrived at MUC I had to go through screening to get my connecting flight to RMI. Wasn't as bad as a TSA search, but still almost caused us to miss our connection...

Coming back from RMI, not only did I get searched again at MUC (thorough too, "Please turn the camera on and show me a picture, while at the same time they fondled my CPAP, but they were as courteous as they were thorough, the TSA could take lessons), but when I got to IAD, after clearing customs (Damned x-ray the bags when telling them we had chocolate...never again) we got the TSA invasion.

While I suppose it makes sense, it's a PITA.

Yes, yet the fact remains that this is a necessary security measure unlike many others.

I disagree with those who cite countries' security as a reason. All inbound passengers to the United States are screened to a standard set by the TSA; the TSA can mandate whatever level of security they want and other countries will comply (we know this from experience). If the TSA thinks that the level they currently mandate is not sufficient for travel within the USA (ie. that connecting passengers need to be rescreened even if they do not touch their checked luggage) then clearly there is a problem with the level of security they mandate for flights inbound to the USA.

Whenever you have access to your checked luggage, you are no longer in a sterile area.

There are a ton of things (some already identified) you can have in your checked luggage you can not carry onto an airplane in your carry on.

This is one check that makes perfect sense.

But why do I have to have access to my checked luggage on an INTL-INTL connection?

Last time I went to Canada LHR-BOS-YYZ, I had to enter US, clear customs and recheck my bag before departing for Toronto.

When I travel BHX-FRA-BEG, I don't [have to] see a German immigration, customs or my checked luggage in Frankfurt.

Because... like it or not.. US airports don't have sterile transit areas...

In fact there often doesn't seem to be any segregation of arrival/departure areas or domestic/International.....

Just the way it is..

The US and Canada has you clear customs (therefore have access to your luggage) and immigration in your landing airport. European countries don't combine the two, so you can clear immigration in landing airport but customs in the second. My trip to EDI was like that - cleared immigration in LHR but customs in EDI. Although "clearing" is an overstatement. They had a segregated baggage claim and a phone to call someone if you were over your limit. No other separation or security at all that was visible.

Other than the UK, which country(ies) are you referring to?