  Earlier, the screening condition in neutron star core has been formulated as
equality of velocities of superconducting protons and the electrons
$\mathbf{v}_p=\mathbf{u}_e$ at wavenumbers $q\ll\lambda^{-1}$ ($\lambda$ is the
London penetration depth) and has been used to derive the force exerted by the
electrons on a moving flux tube. By calculating the current-current response, I
find that $\mathbf{v}_p\neq\mathbf{u}_e$ for $l^{-1}<q\ll\lambda^{-1}$ ($l$ is
the electron mean free path). I show that at typical realistic parameters the
electric field induced by a moving (relative to the electrons) flux tube is not
screened by the electron currents. The implication is that the existing picture
of the momentum exchange between the electrons and the flux tubes must be
reassessed.
