With regards to canon, wasn't at least one US Coast Guard ship mentioned in Rifle River? (Yes, I know technically that wouldn't be part of the US Navy
)
Also it's been years since I read Satellite Down so I can't remember if the USS Virginia was on its own or was part of a small group of ships? Didn't they get into a fight with some Soviet warships? Is the Virginia listed as the only survivor?
An escort for the ships going to the Middle East makes sense.
I'm not convinced about Korea...there would certainly have been a task force there at some point in time, but how much of it would be left by 2000 is probably debatable.
Targan, I could be mistaken here (I'm at work at the moment so all of the above is from memory) but I think the US personnel in the UK were uplifted at the same time as the main Omega evacuation - I think there is reference in the Survivor's Guide to the UK to one or more of the Omega ships making a stop off in the UK to pick up US personnel.