  Consistent interactions between Yang-Mills gauge fields and an abelian 2-form
are investigated by using a Hamiltonian cohomological procedure. It is shown
that the deformation of the BRST charge and the BRST-invariant Hamiltonian of
the uncoupled model generates the Yang-Mills Chern-Simons interaction term. The
resulting interactions deform both the gauge transformations and their algebra,
but not the reducibility relations.
