  We show that all three conditions for the cosmological relevance of heterotic
cosmic strings, the right tension, stability and a production mechanism at the
end of inflation, can be met in the strongly coupled M-theory regime. Whereas
cosmic strings generated from weakly coupled heterotic strings have the well
known problems posed by Witten in 1985, we show that strings arising from
M5-branes wrapped around 4-cycles (divisors) of a Calabi-Yau in heterotic
M-theory compactifications, solve these problems in an elegant fashion.
