> I'm unsure of what source would be appropriate here. I can't point you to a lack of a thing, by definition.

1. You can point to a source with some authority talking about the lack of a thing. Which shouldn't be too hard, since, unless you're ex-Russian Army logistics, you must have learned those claims from somewhere.

2. You can point to a source talking talking about Russian Army logistics, that shows them "moving things by hand" when forklifts would be more appropriate.

3. You can point to a source talking about how all forklifts require really flat concrete, and not all countries can make it because [reasons]. However, you probably can't do that because that would contradict the example I gave of a forklift operating on gravel.