Plain clothes Iranian security forces have rounded up thousands of people in a campaign of mass arrests and intimidation to deter further protests after crushing the bloodiest unrest since the 1979 Islamic Revolution, sources told Reuters. Authorities cut internet access and stifled the unrest with overwhelming force that killed thousands, according to rights groups. Tehran blames “armed terrorists” linked to Israel and the United States for the violence. AdvertisementWithin days, plain clothes security forces launched a campaign of widespread arrests accompanied by an intensified street presence based around checkpoints, according to five activists who spoke on condition of anonymity ⁠from inside Iran. Photo: Middle East Images via AFPThey said detainees had been placed in secret lock-ups.