  We argue that tachyon-free type I string vacua with supersymmetry breaking in
the open sector at the string scale can be interpreted, via S and T-duality
arguments, as metastable vacua of supersymmetric type I superstring. The
dynamics of the process can be partially captured via nucleation of
brane-antibrane pairs out of the non-supersymmetric vacuum and subsequent
tachyon condensation.
