That's a good possibility. Someone could look at the dates on the images already for license.
Most likely older uploads when rules were different.
JPSDK has one right answer. Maybe the safest all around.
Even though the military bought and used these, it's not a Govt. funded project (like NASA Etc.) which means P-41 Mustang for example,
North American Aviation owns the rights to the design. They are now part of Boeing.
Reason for mentioning that is sometimes companies go out of business and the designs fall into public domain. The military markings should not be protected, but the plane design itself is.
Another viewpoint is, that Boeing isn't going to chase people around for using a photo of their old airplanes. I suppose someone could write and ask them for a release? In which case, you might have an advantage over other non-released versions?