If you are ONLY going to AC, you don't need to take ANYTHING (except your bug spray, lotion or whatever).
If you are going into the bush and likely to be exposed to malaria vectors, CHLOROQUINE is what you take. Not doxycyline. If some MD is telling you otherwise, sorry but he is wrong. In this day and age, patients have to take responsibility for their own medical care and do their own research.
Doxycycline is an alternative if you are going into the bush in a country where there is CHLOROQUINE RESISTANT malaria (NOT Belize, there is no choloroquine-resistant malaria in Belize anywhere to anyone's knowledge) and if there is no other prophylactic for choloroquine resistant malaria available. It is used thusly primarily in ASIA, where chloroquine resistant malaria is endemic. It should NOT be taken by someone going to Belize.
You spoke of "military," why not read what the US Navy says about all this. Go to
www.malaria.org and do a bit of searching til see the US Navy splurb on prophlactics.
Look, the info is out there. If you don't believe any of us, do your own research.
Understand the difference between taking a medication to address a clear and present danger to your health, and taking it to make you "feel" better when there is no medical reason to do so. You need to consider the risks and benefits of that approach as well.
I think we've all worked this thread to death. Again:
www.malaria.org has a wealth of info for you. Do your own research.