  We describe a new mechanism, whose ingredients are realised in string
compactifications, for the formation of cosmic (super)string networks.
Oscillating string loops grow when their tension $\mu$ decreases with time. If
$2H + \dot{\mu}/\mu < 0$, where $H$ is the Hubble parameter, loops grow faster
than the scale factor and an initial population of isolated small loops (for
example, produced by nucleation) can grow, percolate and form a network. This
condition is satisfied for fundamental strings in the background of a kinating
volume modulus rolling towards the asymptotic large volume region of moduli
space. Such long kination epochs are motivated in string cosmology by both the
electroweak hierarchy problem and the need to solve the overshoot problem. The
tension of such a network today is set by the final vacuum; for
phenomenologically appealing Large Volume Scenario (LVS) vacua, this would lead
to a fundamental string network with $G \mu \sim 10^{-10}$.
