Complex sentence: In 1991, with the Cold War having come to an end, the Peacekeeper rail garrison system was cancelled, and all 100 Peacekeeper missiles were installed in former Minuteman silos.
Split into simpler sentences: In 1991, however, with the Cold War having come to an end, the Peacekeeper rail garrison system was cancelled. As a result, all 100 Peacekeeper missiles were installed in former Minuteman silos.