[digikata]

Don't feel guilty, the US underfunds basic research as is, if you happen to capture some funding through the DoD route, all it means is that some of the vast DoD funding had a better chance to affect the general good on a practical basis.

On the other hand, the topic you're researching may have an ethical component in terms of its impact in the world. But identification and evaluation of that is completely independent of your funding source. You could be funded completely privately and still need to examine ethics issues.