Only native-born Americans may use their passports to prove their citizenship when enlisting in the Army National Guard. If you are a naturalized or foreign-born American, your shiny, blue U.S. passport won't mean squat to the Guard. This makes no sense. It's also not the rule for the regular Army. What's going on over at the Guard?
As highlighted by the recent news that two stolen passports were used by passengers aboard the missing Malaysia Airlines flight, your passport might well have as much, if not more, value to criminals here and abroad precisely because they are so difficult to obtain and increasingly hard to counterfeit.
I have been cursed at a Chinese border. In Dubai, my passport was studied by three veiled women for over an hour and my suitcase completely dismembered. In the Philippines I had to bribe someone in order to get my visa extended for a few days. But never, ever, will I return to the United States of America.