Calling it the Department of War is accepting that Trump's the King.
If that's not legal, I'll do my best to act shocked.
> (a) The Secretary of Defense is authorized the use of this additional secondary title — the Secretary of War — and may be recognized by that title in official correspondence, public communications, ceremonial contexts, and non-statutory documents within the executive branch.
> (b) The Department of Defense and the Office of the Secretary of Defense may be referred to as the Department of War and the Office of the Secretary of War, respectively, in the contexts described in subsection (a) of this section.
[1] https://www.whitehouse.gov/presidential-actions/2025/09/rest...
> Within 60 days of the date of this order, the Secretary of War shall submit to the President (...) a recommendation on the actions required to permanently change the name of the Department of Defense to the Department of War. This recommendation shall include the proposed legislative and executive actions necessary to accomplish this renaming.
It may currently be a second name, but the explicit intention is for it to become the only one. In HN terms I'd argue that saying "there is no Department of War" is akin to arguing that a piece of software doesn't have feature X because it's only available in the beta release.