  The inner region of the accretion disk around a magnetized neutron star is
subjected to magnetic torques that induce warping and precession of the disk.
These torques arise from interactions between the stellar field and the induced
electric currents in the disk. We carry out a global analysis of
warping/precession modes in a viscous accretion disk, and show that under a
wide range of conditions typical of accreting X-ray pulsars, the magnetic
warping torque can overcome viscous damping and make the mode grow. The
warping/precession modes are concentrated near the inner edge of the disk (at
the magnetosphere-disk boundary), and can give rise to variabilities or
quasi-periodic oscillations (QPOs) in the X-ray/UV/optical fluxes from X-ray
pulsars. We examine the observed properties of mHz QPOs in several systems
(such as 4U 1626-67), and suggest that some hitherto unexplained QPOs are the
results of magnetically driven disk warping/precession.
