You know that Cuba, China and Venezuela don't only trade with other socialist countries right? Actually I'm glad you brought up Venezuela, because their biggest trading partner is literally the USA, the same is true for China, but they've got several other large partners besides the US. International trade is something that happens regardless of your government's political leaning, and nearby nations will always prefer trading with each other due to simple pragmatism, unless there is an exceedingly rare situation, like war or severe embargoes.

You'd be surprised how much produce worldwide is shipped from China. Garlic is a big one.