  We study the free boundary problem for the plasma-vacuum interface in ideal
compressible magnetohydrodynamics. Unlike the classical statement, when the
vacuum magnetic field obeys the div-curl system of pre-Maxwell dynamics, we do
not neglect the displacement current in the vacuum region and consider the
Maxwell equations for electric and magnetic fields. We show that a sufficiently
large vacuum electric field can make the planar interface violently unstable.
We find and analyze a sufficient condition on the vacuum electric field that
precludes violent instabilities. Under this condition satisfied at each point
of the unperturbed nonplanar plasma-vacuum interface, we prove the
well-posedness of the linearized problem in anisotropic weighted Sobolev
spaces.
