I assume that if a ship runs into particles without a deflector, this would amount to drag on the ship's forward motion.

However, a deflector field presumably moves particles sideways (perpendicular to the ship's forward path).

Would the particles still impart drag on the ship's forward motion? If not, what effect would they have?

(For the purposes of this question, let's please ignore the fact that particles colliding with the ship at relativistic speeds would be devastating. I am just interested in whatever action-reaction force is going on here.)