Lattice QCD calculation of $K\to\pi\pi$ decays*

Recent lattice QCD calculations of $K\to\pi\pi$ decays by the RBC/UKQCD collaboration are described, including $\Delta I=3/2$ transitions at physical kinematics and $\Delta I = 1/2$ transitions at threshold. New techniques for the latter and calculations in-progress at physical quark masses are presented. Prospects for a complete calculation of the $\Delta I = 1/2$ rule and direct CP violation in K decays ($\epsilon^\prime$) are discussed.