  We reconsider the dynamics of p anti-D3 branes inside the Klebanov-Strassler
geometry, in which M units of R-R 3-form flux and K units of NS-NS 3-form flux
are presented in deformed conifold. We find that anti-D3 branes blow up into a
spherical D5-brane at weak string coupling via quantum tunnelling. The D5-brane
can be either stable or unstable, depending on number of background flux. The
nucleation rate of D5-brane is suppressed by \exp{-Mp^2}. The classical
mechanically the evolution of unstable D5-brane annihilates one unit of R-R
flux and ends with (K-p) D3-branes. This observation is consistent with one by
Kachru, Pearson and Verlinde, who shew that anti-D3 branes in KS geometry can
blow up into a spherical NS5 brane at strong string coupling, because NS5-brane
is lighter that D5-brane at strong string coupling. We also argue that the
system can end with a meta-stable dS vacuum by fine tuning of number of
background flux.
