  The azimuthal elliptic asymmetry v2 observed in heavy ion collisions, is
usually associated with properties of the medium created in the final state. We
compute the azimuthal asymmetry which is due to multiple interactions of
partons at the initial stage of nuclear collisions, and which is also present
in $pA$ collisions. In our approach the main source of azimuthal asymmetry is
the combination of parton multiple interactions with the steep variation of the
nuclear density at the edge of nuclei. We apply the light-cone dipole formalism
to compute the azimuthal asymmetry of prompt photons yield from parton-nucleus,
proton-nucleus and nucleus-nucleus collisions at the RHIC energy.
