  We interpret the recent hints for lepton flavor universality violation in
rare $B$ meson decays. Based on a model-independent effective Hamiltonian
approach, we determine regions of new physics parameter space that give a good
description of the experimental data on $R_K$ and $R_{K^*}$, which is in
tension with Standard Model predictions. We suggest further measurements that
can help narrowing down viable new physics explanations. We stress that the
measured values of $R_K$ and $R_{K^*}$ are fully compatible with new physics
explanations of other anomalies in rare $B$ meson decays based on the $b \to s
\mu\mu$ transition. If the hints for lepton flavor universality violation are
first signs of new physics, perturbative unitarity implies new phenomena below
a scale of $\sim 100$ TeV.
