I am posting this here to try and get the quickest response...

My girlfriend may need to travel to Guam from work. The two options of getting there is flying through HNL or NRT.

If she flies through NRT does she need to go through Japanese customs and thus need a passport with her even though she is just passing through with her final destination being US soil?

If flying to GUM via NRT, she will NOT need to enter Japan. No need for Japanese customs and immigration. She will need to clear transit security in NRT.

She will need to have her passport with her. As, she will "re-enter" the USA in Guam and go through US Immigration and clear customs upon landing in GUM.

Same with her return flight via NRT. Just transit security in NRT and then clear US Immigration and Customs upon return to the US Mainland.

If she goes via HNL, she will need to clear Guam Customs upon entry into GUM. There is no immigration check in GUM. I believe that no passport is necessary.

On the return, upon landing in HNL, she will need to clear US Customs in HNL. There is no immigration check in HNL.

Does transit security allow laptops to stay inside "checkpoint friendly" bags?

I FINALLY bought one and I can't recall seeing someone use one there.

This is correct. I have a friend who goes to GUM all the time from HNL and he never brings his passport. I have flown NRT-GUM and they did check my passport at that time.

I left mine in there the last couple of times and they didn't object but ymmv.

I think you'll be okay - Singapore made me take mine out though.

OP, even if possible I think it is luducrous to try this w/o a passport. Will they even allow her to board the NRT flight both ways? Do they check the passport at the NRT gate? IROPS?

Way to many chances for a travel disaster.

It takes 5 (or less) days to expedite a passport. Do so and charge the expedite fee to the company travel.

However, there is an immigration preclearance in GUM, where they will verify admissibility to the US (50+DC+PR). A passport is not "required" for US nationals, but relevant documents are recommended.

IIRC transit security in NRT checks to see if you have a passport as well and good luck trying to talk your way out of that one.

I go to Guam every year, usually through HNL. I went through NRT once and had to show my passport to board SFO-NRT and NRT-GUM. I also had to show it when I arrived in Guam and when I departed Guam. There have been other posts on FT stating you only need a birth certificate if you're just transferring through NRT. YMMV

Personally I wouldn't go through NRT without a passport.

She has a passport....just checking to remind her that if she needs to bring it with her. If she happened to have misplaced it she needs to get one expedited. If she goes through HNL she doesnt need it.

she would not be let on a flight to Japan without a passport, transit or not

I fly to Guam from LAX 5-6 times a year. LAX-HNL-GUM is the most efficient way for me. However, if there are IRROPs involving LAX-HNL, then LAX-NRT-GUM is an alternative that will get you into GUM at 1am as opposed to 6-7 pm.

In order To be rerouted through NRT you need a passport. Otherwise you can be stuck in HNL for a day.
Similarly, if the GUM-HNL flight is canceled, a passport would be needed to go back via NRT.

The airlines will not allow her onto a flight to NRT without a passport. How do they know that she's really going to transit to Guam?

Presumably because she has an onward booking on the same PNR, and could not get out of the transit area without a passport.

I think the bigger issues, at least theoretically, are that (a) the immigration people in Guam would not know where she had come from, and (b) if anything happened along the way, she might be forced to enter Japan for lodging, medical treatment, etc.

BTW, this website seems to say that if you are in the military, you are allowed to transit NRT to get to GUM without a passport. Note that it seems dated (it refers to flying NW) but does note that civilians need passports: http://usmilitary.about.com/od/airfo...Andersen_2.htm