  The emission from an electron in the field of a relativistically strong laser
pulse is analyzed. At pulse intensities of J > 2 10^22 W/cm2 the emission from
counter-propagating electrons is modified by the effects of Quantum
ElectroDynamics (QED), as long as the electron energy is sufficiently high: E >
1 GeV. The radiation force experienced by an electron is for the first time
derived from the QED principles and its applicability range is extended towards
the QED-strong fields.
