  This letter is about confinement in QCD. At the moment we have pictures of
confinement to complete our understanding of the physics of strongly
interacting particles, interaction which asks for confinement. As it is said in
[1] : " In principle it should be possible to derive the confinement hypothesis
from the QCD Lagrangian. At this time, no rigorous derivation exists, so it is
not absolutely clear that the confinement hypothesis is a bone fide prediction
of QCD" . In this letter we show that a sufficient (of course not necessary)
condition for confinement is that topological structure of vacuum in Nature
does not correspond to the $\theta$-vacuum. Therefore, if different vacua with
nontrivial winding number cannot be connected by tunneling, we obtain
confinement as a consequence.
