DIA is an acronym that now means “Drowning in Acronyms”. DIA originally stood for the Defense Intelligence Agency, but now it just describes their mode of speech. DIA and the rest of our government (and much of industry) talk glibly about UAVs and IEDs, and so on. They know what this alphabet soup of abbreviations means. To them it all is quite obvious.
They forget that we do not understand most of what they are saying. If you absolutely must use an acronym in a speech, then please take a few seconds to define it. As a general rule please AAIP (Avoid Acronyms If Possible). Your audience will thank you.
Some of the most obscure acronyms are drifted names for technical societies. An acronym originally stood for the name. Then the name changed, but the acronym did not. Presumably this is due to the complexities of American trademark law. However, it is just wonderful for confusing outsiders. For example, I am a member of TMS which originally was The Metallurgical Society. Now TMS actually is The Minerals, Metals, and Materials Society.
It gets worse. Over in Great Britain there used to be the Institute of Metals, IOM. Now it is IOM3, meaning the Institute of Materials, Minerals, and Mining. The newer alphanumerical soup is worse, and should be avoided even in Business to Business (B2B) communication.