  We consider the ${\mathcal O}(1/m)$ and the spin-independent
momentum-dependent ${\mathcal O}(1/m^2)$ quasi-static energies of heavy
quarkonium (with unequal masses). They are defined nonperturbatively in terms
of Wilson loops. We determine their short-distance behavior through ${\mathcal
O}(\alpha^3)$ and ${\mathcal O}(\alpha^2)$, respectively. In particular, we
calculate the ultrasoft contributions to the quasi-static energies, which
requires the resummation of potential interactions. Our results can be directly
compared to lattice simulations. In addition, we also compare the available
lattice data with the expectations from effective string models for the
long-distance behavior of the quasi-static energies.
