Iran has warned it will retaliate if attacked by the US, as protesters defied a deadly government crackdown on Saturday night. Videos verified by the BBC and eyewitness accounts appeared to show the government ramping up its response to the protests, which have spread to more than 100 cities and towns across every province in Iran. Medics at two hospitals have told the BBC that more than 100 bodies had been brought in over a two day period. The nationwide death toll is feared to be far higher. The US has threatened to strike Iran over the killing of protesters....