The hijab headscarf became obligatory for all women in Iran in April 1983, four years after the 1979 revolution that overthrew the US-backed monarchy.Hundreds killedAfter the hijab law became mandatory, with changing clothing norms it became commonplace to see women in tight jeans and loose, colorful headscarves.Iran accuses its sworn enemy the United States and its allies, including Britain, Israel, and Kurdish groups based outside the country, of fomenting the street violence which the government calls "riots".Oslo-based non-governmental organization Iran Human Rights on Tuesday said at least 448 people had been "killed by security forces in the ongoing nationwide protests".UN rights chief Volker Turk said last week that 14,000 people, including children, had been arrested in the protest crackdown."