Sorry, it addressed the validity of the letter, but I should have looked farther down the page.
chookter, Marines can read and write /humor. Actually, given the tense changes "The Marines" next "We", I'd say it's bogus. Even with lousy writing skills, you don't alternatively refer to yourself that way. And an Embassy Guard wouldn't refer to other guards as the Marines.
On the long shot that its valid, in a unit that small, someone is in a world of something right now.