Iran has resumed enriching uranium to 20% purity, in its most significant breach yet of the 2015 nuclear agreement with world powers. Government spokesperson Ali Rabiei told Mehr news agency that the process had started hours ago at the underground Fordo facility near Qom. Enriched uranium can be used to make reactor fuel but also nuclear bombs. Weapons-grade uranium is 90 percent purity. There was no immediate confirmation from the global nuclear agency.