  Quarkonium production is a sensitive probe of the dynamics of hard
scattering, which can `measure' the environment of the heavy quark pair after
it is created in a hard process. Quarkonium hadroproduction data indicates that
the produced pair experiences a secondary, hard interaction and then ceases to
interact at a stage when the pair is still compact (compared to the size of the
quarkonium wave function). These features differ from scenarios mostly
discussed so far. An approach which relies on an early, perturbative
rescattering of the pair with a comoving color field can explain many observed
features, including the polarization, the $\chi_1/\chi_2$ ratio and the nuclear
target $A$-dependence, which are difficult to understand otherwise.
