  We argue that the radiative energy loss of a parton traversing the
quark-gluon plasma is determined by Landau damping of soft modes in the plasma.
Using this idea, we calculate the jet quenching parameter of a gluon. The
calculation is done in SU(3) quenched QCD within the stochastic vacuum model.
At the LHC-relevant temperatures, the result depends on the gluon condensate,
the vacuum correlation length, and the gluon Debye mass. Numerically, when the
temperature varies from T=T_c to T=900 MeV, the jet quenching parameter rises
from \hat q=0 to approximately 1.8 GeV^2/fm. We compare our results with the
predictions of perturbative QCD and other calculations.
