  We present two examples of the short-distance QCD calculations for the
quarkonium (\Phi) interactions; 1) \pi \Phi elastic and \pi \Phi -> \pi \Phi'
cross sections, and 2) the potential between two \Phi's. The former is relevant
for the \Phi suppression in heavy ion collisions; we find that the
corresponding cross sections are very small. For the latter we derive the sum
rule which relates the strength of the potential to the energy density of the
QCD vacuum. The key starting point in both cases is that the leading operator
in the operator product expansion (OPE) for the low--energy scattering
amplitude is the trace of the QCD stress tensor whose matrix elements are
unambiguously fixed by the low energy theorem. The resonances in the two-pion
scalar channel are taken into account as a formfactor.
