  It is shown that a constant external magnetic field, generally speaking, is
not able to prevent breaking (loss of smoothness) of relativistic plasma
oscillations, even if they are arbitrarily small perturbations of the zero
steady-state. This result sharply differs from the non-relativistic case, for
which it is possible to suppress the breaking of oscillations at any initial
deviations by increasing the intensity of the magnetic field \cite {RCharx}.
Nevertheless, even in the relativistic case, there are subclasses of solutions
corresponding to solutions that are globally smooth in time.
