  QCD perturbation theory ignores the compact nature of $SU(3)$ gauge group
that gives rise to the periodic $\theta$-vacuum of the theory. We propose to
modify the gluon propagator to reconcile perturbation theory with the anomalous
Ward identities for the topological current in the $\theta$-vacuum. As a
result, the gluon couples to the Veneziano ghost describing the tunneling
transitions between different Chern-Simons sectors of the vacuum; we call the
emerging gluon dressed by ghost loops a "glost". We evaluate the glost
propagator and find that it has the form $G(p) = (p^2 + \chi_{top}/p^2)^{-1}$
where $\chi_{top}$ is the Yang-Mills topological susceptibility related to the
$\eta'$ mass by Witten-Veneziano relation; this propagator describes
confinement of gluons at distances $\sim \chi_{top}^{-1/4} \simeq 1$ fm. The
same functional form of the propagator was originally proposed by Gribov as a
solution to the gauge copies problem that plagues perturbation theory. The
resulting running coupling coincides with the perturbative one at $p^2 \gg
\sqrt{\chi_{top}}$, but in the infrared region either freezes (in pure
Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with
experimental evidence. Our scenario makes explicit the connection between
confinement and topology of the QCD vacuum; we discuss the implications for
spin physics, high energy scattering, and the physics of quark-gluon plasma.
