Large crowds protested against the Iranian regime in Tehran and across the country. Videos on social media show crowds marching peacefully in Tehran and Mashhad, Iran's second largest city. The demonstrations are said to be the biggest by regime opponents in years. Protesters in Mashhad demanded the overthrow of Supreme Leader Ayatollah Ali Khamenei and called for the return of Reza Pahlavi, son of the late former shah. Reza Pahlavi had urged supporters to join the protests. The unrest is now on its 12th day. It has spread to 140 cities and towns across all 31 provinces, according to the US-based Human Rights Activist News Agency (HRANA). HRANA reports at least 34 protesters and 7 security personnel have been killed, with 2,270 protesters arrested. Norway-based Iran Human Rights says at least 45 protesters, including eight children, have died. BBC Persian confirmed 21 deaths with identified victims, while Iranian authorities reported 5 security personnel deaths. The protests began on 28 December when Tehran shopkeepers protested the sharp fall in the Iranian rial against the US dollar. The rial has hit record lows this year. Inflation has soared to 40% due to US sanctions over Iran's nuclear program, government mismanagement, and corruption. University students soon joined the protests, chanting slogans against the clerical regime. Despite some violent clashes earlier, recent footage shows peaceful crowds undeterred by security forces. This wave of demonstrations marks the largest public opposition to the Iranian regime since the disputed 2009 presidential election protests.