Nepal, Jan. 14 -- International outrage has built over a crackdown on the demonstrations, which a rights group said has likely killed thousands in one of the biggest challenges yet to Iran's clerical leadership.

Iran on Wednesday vowed fast-track trials for people arrested over a massive wave of protests, after US President Donald Trump threatened "very strong action" if the Islamic republic goes ahead with hangings.International outrage has built over a crackdown on the demonstrations, which a rights group said has likely killed thousands in one of the biggest challenges yet to Iran's clerical leadership.

Iranian authorities have insisted they have regained control of the country after successive nights of mass protests, repeatedly acc...