Prove the red blue separation problem is NP-complete

Question

Consider the following problem: given a set of $m$ red points and $n$ blue points in the plane, find a minimum length cycle that separates the red points from the blue points. That is, the red points are inside the cycle and the blue points are outside the cycle, or vice versa. This problem is called the red blue separation problem.

I am trying to reduce the Traveling Salesman Problem (TSP) to this but I am getting nowhere. Can you please help me with this? Any help is appreciated.