How is this any different than the war economy Russia has found themselves in? https://archive.fo/0VJ6J
Wouldn't outside investment help rebuild Ukraine after the war? https://www.reuters.com/world/europe/western-nations-commit-billions-help-rebuild-ukraine-2023-06-21/
These factories are also able to be retooled to build other goods, cars, tractors, silverware, if they're rocket or missile plants they can be retooled to make furnishings or hell even fertilizer. https://www.history.com/news/post-world-war-ii-boom-economy
Also it seems a lot of western firms are funding Russias war efforts. https://time.com/collection/time100-voices/7097457/western-firms-funding-russian-war-ukraine/