  Using the lattice Schr\"odinger functional we study vacuum dynamics of SU(3)
gauge theory at finite temperature. The vacuum is probed by means of an
external constant Abelian chromomagnetic field. We find that by increasing the
strength of the applied external field the deconfinement temperature decreases
towards zero. This implies that strong enough Abelian chromomagnetic fields
destroy confinement of color.
