Authorities in Iran say they could intensify their crackdown on the biggest anti-government protests in years, blaming what they call "terrorists" and vowing to protect the Islamic regime.

One human rights group says at least 192 protesters have died since the demonstrations began two weeks ago — amid warnings the actual death toll could be several hundred.

US President Donald Trump has again warned he could intervene — saying America stands ready to help — as reports of violence and an internet blackout make the situation hard to verify.

Despite that, new videos suggest protests are still spreading across Tehran and other cities, with the exiled son of the former shah urging Iranians to turn the unrest into a full-scale revolt.

• Guest: Gregg Carlstrom is a Middle East Correspondent for The Economist
• Producer: Anne Barker