Sure. At one time I was working to support my wife and myself through our Ph.D. programs. The work was in applied math and computing on mostly US Navy problems. At one time, there was an urgent request: Evaluate the survivability of the US SSBN fleet under a controversial scenario of global nuclear war limited to sea.
Point: A claim is that if find an SSBN, then can kill it with a nuke -- likely true. Another claim is that can't find an SSBN -- not really true but close to true since a promising effort to find the SSBNs would be 'provocative' and raise alarms. Also, if find and sink one, then that's the start of nuclear war, and the other SSBNs will be free to fire. So, what is tough is to find all the SSBNs at one time and sink them all at once. But if in the special scenario, then could find and sink the SSBNs one at a time. Then how long would they last?
The Navy wanted their answer quickly, in two weeks. That was about right, since my wife already had us scheduled for a vacation cabin in Shenandoah starting the day after the due date!
So, I derived some math, wrote some software, and both the Navy and my wife got what they wanted on time!
My understanding is that my work was later sold to another group interested in US national security. I could tell you what that group was, but then I'd have to ...!