# Is Rectilinear Steiner Tree still NP-complete when points have integral coordinates?

Garey proved that the Rectilinear Steiner Tree problem is (strongly) NP-hard. I wonder if it is still true when we retrict the points to have integral coordinates and lie on a square of side lenght n^O(1) where n denotes the number of points.

I just browsed through the proof by Garey and Johnson. It is clear that, in fact, they build their proof on the rectilinear stree problem with integral coordinates within a square of side length $$n^{O(1)}$$, where $$n$$ denotes the number of points.