My experience in the aerospace/defense industry suggests that this isn't really practical. Organizations that make aircraft and rockets and weapons tend to be incredibly conservative: they don't really innovate much. They have incredibly risk averse institutional cultures...no one wants to be the guy that decided to launch Challenger.

I know of one aerospace company that occasionally has its rockets explode on the launchpad because they use battery designs from the 1970s that are known to explode with fairly high probability. They could easily get much cheaper much more reliable batteries with more modern designs but they don't because the exploding batteries "have flight heritage". This particular aerospace company is considered agile and nimble and innovative compared to its competitors.

Speaking for the U.S. context only: once you have a security clearance, which will become necessary at some point for defence work, it becomes difficult to move out to non-classified work. On one hand, the pool of people with clearances is smaller than the general labor pool, so you can have a higher salary & benefits, therefore it's more attractive to stay at that kind of work. On the other hand, prospective employers outside defence likely do not have clearances and so cannot learn anything about what you did - this makes it difficult to leverage your experience when seeking to move to a new job.

I don't work in defence. That is just what I've heard from people who do as one of the reasons why it's hard to "rotate in, rotate out."

You are correct (IME) in your first point, about the difficulty of moving away from the high salary and benefits associated with cleared jobs, but not really on the second one.

Doing secure work means you can't take any confidential information with you when you leave, and it might slightly limit what you can talk about, but it doesn't mean you can't say anything about the work you did. You can still talk about your role and skillset, usually about the languages and technologies (and COTS products) used.

Many government IT projects mandate security-cleared developers because the systems touch classified information, but that doesn't mean that the systems themselves (their existence, basic design, etc.) are classified. There's really no difference between having a project like that on your resume, and any other commercial-sector project that's internal use only.

If you're working or considering working on a clearance-required project, it's not unreasonable to ask to talk with the security officer beforehand to clear up exactly what you'll be able to put on your resume and discuss after the fact ... and price yourself accordingly.

> Speaking for the U.S. context only: once you have a security clearance, which will become necessary at some point for defence work, it becomes difficult to move out to non-classified work.

Huh? None of my friends with clearances seem to have that problem. Do they have the "wrong" clearances?

Not sure that it would make a difference whether your employer has a security clearance or not. If you're following "need-to-know" doctrine, then you still wouldn't tell them.

Not all knowledge obtained by working in a defense organism would be transferable. You get probably less useful real-world knowledge by working there rather than any other place.

OK, who installed the laser turrets in the server room?

I would disagree with that -- as just one example, modern chemotherapy is derived from the development of mustard gas circa World War I.

These companies are really set up to prevent people from doing this.