  A graph has \emph{diameter} D if every pair of vertices are connected by a
path of at most D edges. The Diameter-D Augmentation problem asks how to add
the a number of edges to a graph in order to make the resulting graph have
diameter D. It was previously known that this problem is NP-hard \cite{GJ},
even in the D=2 case. In this note, we give a simpler reduction to arrive at
this fact and show that this problem is W[2]-hard.
