More Force Awakens spoilers:
So does anyone have any idea what was up with all the red hands in this movie?
A storm trooper marks Finn's helmet with a bloody handprint at the start of the movie (which was an excellent way to make him identifiable in the following scenes.)
C-3PO calls attention to his new red arm.
The death beam from the Starkiller is no longer the perspective-line style focus of previous Death Star imagery, but a thick red beam which splits into five smaller beams that reach out to their targets.
Kylo's red lightsaber famously spreads out in the same way.
Less strongly, Kylo's hand gets a lot of emphasis of how he uses the Force, and while he's monochromatically black, red is the other color most associated with the Sith.
I just don't really know why, as it undercuts a lot of the blatant Nazi imagery with more traditional Soviet symbolism.