I was referring to the previously posted Homeland Security documents describing them, since they are the enforcers.
As an update to this, while it may(?) be within their purview should it come to their attention, DHS is not the ones chasing this. It is the DOD, Criminal Investigations. They are, among other things, tasked with "bringing home" "lost" military items that they deem could be advantageous to a foreign govt. This includes items that may qualify as antiques, items legally purchased that the possessor may have a receipt for (to include from property disposal), books, pictures, etc.
Nearly a year ago I had the opportunity to ask a few questions to one of these officers (DOD Civilian CI), he stated that post 9-11 a number of laws were passed, (not only the Patriot Act) which were specifically written in a very general manner. These laws allow them great latitude in interpretation and enforcement. Over the years a lot of things have been released or walked away from the government that should not have gotten out. Part of our job is to get them back. As he stated it, we cannot seize anything, but we can ask for it. The act of refusing to turn it over when asked is itself a felony.
I've attached the text of one of the references that he identified, with a few highlighted areas. Recognize that the items discussed could fall under the category of "model, instrument, appliance" etc. As you read through this pay attention to the fact that there are no boundaries, no restrictions, everything is left to the determination and discretion of the officer standing in front of you at the time. He is required no training in the subject, common sense does not have to come into play. Items related to the "big three" seem to be of the highest priority, with tech pieces coming in next, but there appears to be nothing that restricts them to that. As stated by the officer I was speaking to, "If we want it, you will give it to us. You are welcome to go to court to try to get it back, people do all the time. I've been doing this for 30 years and nobody has ever won."
Google the law for the full text, penalties, etc. and keep in mind that it is not the only regulation that they use. Also, you don't get to interpret the law, they do.

