  When D-branes are inserted in flux backgrounds of opposite charge, the
resulting solution has a certain singularity in the fluxes. Recently it has
been argued, using numerical solutions, that for anti-D3 branes in the
Klebanov-Strassler background these singularities cannot be cloaked by a
horizon, which strongly suggests they are not physical. In this note we provide
an analytic proof that the singularity of all codimension-three antibrane
solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3
branes smeared on the T^3 of R^3xT^3 with fluxes) cannot be hidden behind a
horizon, and that the charge of black branes with smooth event horizons must
have the same sign as the charge of the flux background. Our result indicates
that infinitesimally blackening the antibranes immediately triggers brane-flux
annihilation, and strengthens the intuition that antibranes placed in flux with
positive charge immediately annihilate against it.
