  The long standing problem of a non-perturbative renormalization of a gauge
field theoretical Hamiltonian is addressed and explicitly carried out within an
(effective) light-cone Hamiltonian approach to QCD. The procedure is in line
with the conventional ideas: The Hamiltonian is first regulated by suitable
cut-off functions, and subsequently renormalized by suitable counter terms to
make it cut-off independent. Emphasized is the considerable freedom in the
cut-off function which eventually can modify the Coulomb potential of two
charges at sufficiently small distances. The approach provides new physical
insight into the nature of gauge theory and the potential energy of QCD and QED
at short distance.
