The Defense Language Aptitude Battery (DLAB) is the test that the United States (and Australian) military will give you if you are interested in pursuing an MOS/AFSC/Rating that involves a language. This test is currently in its second iteration.
For the most part, those jobs are going to be Intelligence jobs. And within that, they will be dominantly Human Intelligence (HUMINT) and Signal Intelligence (SIGINT) jobs — since speaking directly to non-native English speakers or listening to their communications traffic pretty much means you need to be able to function in something other than English. On the commissioned side, Foreign Area Officers (FAOs) have to pass the DLAB.
The DLAB’s scoring is broken down into five tiers. Those scores will either disqualify you, or qualify you for a Category or “level” of language. The higher your score, the higher the Category (or, Cat)… thus, the more difficult the language the military feels like they can trust you to pass.
The Cats are I – IV. I being “easier” for a native English speaker to learn. IV being “more difficult” for a native English speaker to learn. Cat Is include stuff like French and Spanish — among others. Cat IIs include German and Indonesian. Cat IIIs include Russian, Farsi, and Thai. Cat IVs include Arabic and Mandarin.
Foreign language training for the military occurs at two main installations, and DLAB is your ticket to ride. The Defense Language Institute, Foreign Language Center, Presidio of Monterey, CA (DLIFLCPOMCA); and DLI-Washington, in Washington, DC, (what we used to call DLI-East) are those two schoolhouses. DLI-W is where you would learn low density languages; languages that don’t require the same level of graduation output as the “mainline” languages taught in Monterey.
Having said that, the last class I was in at DLI graduated two (2) people. We had a teacher/student ratio of 2:1. But, that was not considered low density…
There are a number of study guides for the DLAB. But when I took my DLAB waaay back in the 90s, I didn’t even know I was taking it (or even what it was) until they pulled me off a couch in the waiting area of MEPS and sat me alone in an office cubicle with my booklet, two pencils, a cassette tape player, and some skullcrushing Cold War era headphones. I made out okay.
Already knowing a language is no guarantee you’ll pass. Having studied a language (or more) is no guarantee you’ll pass. The test itself doesn’t test your ability in a language… it tests your brain’s ability to learn a new language basically on the fly.
Even if you do go get a study guide, it’s not like a typicaly standardized test study guide. You’re not learning or memorizing subject matter. What you are doing with these guides is learning how the test is given.
If you are interested in following that path, I encourage you to give your options a look. Even if you are planning on joining the military and don’t yet know what path you’ll take, I would absolutely take that test if only to expand (or streamline) your options. I’d also suggest it simply for the experience.
I took mine more than two decades ago, and still have nightmares about it… I’m kidding.