This sounds suspiciously like the kind of project comprising generalizable research as defined by OHRP's Michael Carome in his October 2003 discussion with the UCLA Office for Protection of Research Subjects (as reported by UCLA.) In that conversation, Carome noted that
Systematic investigations involving open-ended interviews that are designed to develop or contribute to generalizable knowledge (e.g., designed to draw conclusions, inform policy, or generalize findings) WOULD constitute "research" as defined by HHS regulations at 45 CFR 46.
[Example]: An open ended interview of surviving Gulf War veterans to document their experiences and to draw conclusions about their experiences, inform policy, or generalize findings.
Except for the fact that it's the wrong Gulf War, the Army study nicely fits Carome's example of research requiring review.
Fortunately for federal historians, no one else in the federal government seems to share Carome's view on this matter. I know of no federal agency, executive or legislative, that requires IRB review for oral histories conducted by its employees. As reported on this blog, even OHRP officials did not submit to IRB review when conducting oral history research.
Maybe Dr. Carome will try to discipline the researchers at Fort Leavenworth. Him and what army?