  The sensitivity of the present CNGS beam to the sub-dominant $\nu_\mu
\leftrightarrow \nu_e$ oscillations in the region indicated by the atmospheric
neutrino experiments is investigated. In particular, we present a revised
analysis of the OPERA detector and discuss the sensitivity to $\theta_{13}$ of
ICARUS and OPERA combined. We show that the CNGS beam optimised for $\nu_\tau$
appearance, will improve significantly (about a factor 5) the current limit of
CHOOZ and explore most of the region
$\sin^22\theta_{13}\simeq\mathcal{O}(10^{-2})$.
