uh uh uhhhhh IDK

What I can say is that American manufacturers are not doing well because the buy-American policy combined with the lack of rolling stock being built means that there are several cases where an entire locomotive plant is built that only produces a few trains and is then shut down again, because most of the domestic rail manufacturers have gone out of business (RIP the Budd Company).

AES countries also give us a hint into how they might work. Cuba does not seem to be able to build new rolling stock thanks to the embargo, and struggles to maintain its railway network. Basically all of the trains are either pre-revolution or an eclectic mix of old rolling stock from around the world. The DPRK does produce its own subway trains but they look a little outdated. China, with its vast industry and large amounts of steel, excels at building trains and has built many over the past decade.

Edit: Actually I take that comment about the Pyongyang Metro back. The new trains look very comfortable on the inside, are clean, modern, seem to have modern inverter propulsion, and most importantly have nice cushy seats, something lacking on Chinese metros.