The X-Men are a team of mutants who follow and defend the dream of the mutant Charles Xavier. Xavier believes that mutants and humans can exist together peacefully. The X-Men work to achieve human-mutant peace and defend humans against mutants who would harm or subjugate them. The X-Men were formed by Professor Charles Xavier who opened his School for Gifted Youngsters in order to train young mutants in the use of their powers. Professor Xavier's original students included Cyclops, Phoenix (then known as Marvel Girl), Angel, Beast, and Iceman. As a result of the Onslaught crisis, the government has officially sanctioned Operation: Zero Tolerance to end the "mutant problem." Its primary mission is to find and capture the X-Men, who have now been branded as outlaws by the American government.