Iran has faced intense nationwide protests for nearly two weeks, marking the largest challenge to the country's ruling regime in years — and drawing vows from President Trump to intervene on the protesters' behalf if they face a violent crackdown.

Initially sparked by Iran's economic freefall and severe inflation, the protests have boiled over, with about 180 cities facing demonstrations. One monitoring group has reported thousands of arrests and dozens of deaths since the protests began.

Here's what you need to know:

How the Iran protests started, and what they've become

The current wave of protests began in the capital, Tehran, in late December as shopkeepers went on strike and marched into the streets. Small business owners in Iran have long been seen as supportive of the regime, but anger over spiraling inflation and the devaluation of the nation's currency, which lost more than 40% of its value last year, making everyday goods impossible for many people to afford, sparked the demonstrations.

The protests quickly spread, with people joining marches across the country to denounce not only the economic woes, but to air wider discontent with the country's hardline regime.

As of Friday, protests were reported in at least 180 cities in all 31 of the country's provinces, according to the Human Rights Activists News Agency, or HRANA, a U.S.-based monitoring group founded by anti-regime activists.

Demonstrations have also been reported on dozens of university campuses since late December, and strikes and shop closures were reported in markets in over a dozen cities, HRANA said.

Videos posted on social media virtually every night have shown crowds of protesters marching through the streets of various Iranian cities, chanting anti-government slogans and clashing with the country's security forces in some cases.

How Iranian authorities have responded

More than 2,300 people have been reported detained since the wave of protests began, including at least 167 under the age of 18, according to HRANA. Some 65 people have been killed, the group said, including 50 protesters, at least seven people under the age of 18 and 14 members of the security services.

The Islamic Republic's semiofficial Fars news agency claimed Monday that about 250 police officers and 45 members of the feared Basij security force had been injured amid the unrest.

Iranian authorities cut off phone service and web access Thursday night across the country, according to the internet monitoring organization NetBlocks, which said a "nationwide internet blackout" continued on Friday.

"Even Starlink, which has been the main line of communication for some activists in different parts of the country, has been jammed," Maziar Bahari, editor of the independent IranWire news site, told CBS News on Friday, referring to the satellite communication system run by Elon Musk.

CBS News has sought comment from SpaceX, which runs Starlink, but did not get any immediate response.

Trump warns he'll hit Iran "very hard" if it kills protesters

Mr. Trump has threatened on several occasions since the protests began that he could order a U.S. intervention if Iranian authorities kill demonstrators. 

Speaking at the White House on Jan. 9, Mr. Trump reiterated that he was open to some kind of U.S. action, although he said that would not involve a U.S. incursion.

"I've made the statement very strongly that if they start killing people like they have in the past, we will get involved," Mr. Trump said. "We'll be hitting them very hard where it hurts. And that doesn't mean boots on the ground, but it means hitting them very, very hard where it hurts. So, we don't want that to happen."

In a Jan. 2 post on Truth Social, he said: "If Iran [shoots] and violently kills peaceful protesters, which is their custom, the United States of America will come to their rescue."

"We are locked and loaded and ready to go," the president said.

Speaking on Fox News on Jan. 8, Mr. Trump said the U.S. was "ready" to hit Iran hard if protesters were killed, but added, "for the most part, they haven't" been.

The president's comments came just over six months after he ordered airstrikes on three Iranian nuclear facilities, amid a deadly days-long conflict between Iran and Israel.

The unrest in Iran also comes as Mr. Trump takes a more aggressive posture on the world stage.

U.S. forces captured former Venezuelan President Nicolás Maduro in an overnight military operation in Caracas on Jan. 3, and Mr. Trump has suggested he's open to military action in Colombia to combat drug trafficking, and even to take control of Greenland.

Alex Vatanka, a senior fellow at the Middle East Institute who studies Iran, told CBS News last week that Mr. Trump's gestures of support could embolden Iranian protesters, saying his comments may be the "one ingredient you need to keep … the street-level movement alive."

Bahari, of IranWire, said Iranian officials had told him they were concerned about Mr. Trump potentially intervening in Iran even before the protests began.

The recent U.S. attack on Venezuela, "has really scared many Iranian officials and may have affected their actions in terms of how to confront the protesters. But at the same time, it has inspired many protesters to come out, because they know that the leader of the world's main superpower is supporting their cause."

Iranian leaders acknowledge problems, but blame U.S.

In an address on state television aired Friday, after an intense night of protests, Iran's Supreme Leader Ayatollah Ali Khamenei vowed that his regime would "not back down," called for unity and accused "a bunch of vandals" in Tehran of causing chaos in the capital "to please the U.S. president."

In some cases, Iranian officials have attempted to strike a conciliatory tone, acknowledging people's economic concerns and insisting that people have the right to protest peacefully. State media reported that President Masoud Pezeshkian had directed security forces not to crack down on peaceful protesters. 

The government has also offered some relief in the form of $7-a-month stipends that can be used in grocery stores to buy basic necessities.

Iran's Ministry of Foreign Affairs has condemned Mr. Trump threats of a U.S. intervention, accusing the U.S. of "inciting violence and terrorism."

Iranian army commander Major General Amir Hatami threatened Wednesday to "cut off the hand of any aggressor."

Iran's history of mass protests 

Protests — and severe crackdowns — are a recurring theme in Iran.

The last major round of protests came in 2022, spurred by the death in police custody of 22-year-old Mahsa Amini, who was arrested by the theocratic government's forces for allegedly wearing her headscarf incorrectly. Hundreds of people were killed across months of demonstrations.

Other protest movements came in 2019 and 2017, and Iran was beset by a large-scale uprising in 2009 over the country's contested presidential election.

"From what we saw on social media channels and also from conversations with different people in Iran, the number of protesters in different parts of the country is not as high as in 2022, but there are more protests — the protests are more widespread in different parts of the country," Bahari told CBS News. "So, even some smaller cities where they never had a protest in those cities, they see protests these days, and I think people are more desperate than before."

The current protests seem different compared to the previous rounds — and could be harder for the regime to quell by offering concessions — due to their roots in the country's economic woes, according to Mona Yacoubian, Director and Senior Adviser of the Middle East Program at the Center for Strategic and International Studies.

She noted that in 2022, the regime was able to appease protesters by "simply addressing their complaints about women's veiling and so forth." 

But the protesters now are more focused on economic problems, and "there's really nothing [the regime] can do" to get Iran's moribund economy back on track, she said.

"These protests, they are about economic situation, but also about dignity," Bahari told CBS News. "It's about the national pride. And because of that, this protest will be very, very difficult to contain."

Iranian Crown Prince Reza Pahlavi cheers on the protests

Iranian Crown Prince Reza Pahlavi, whose father the former shah, fled just before the 1979 Islamic Revolution that brought the current clerical regime to power, has cheered the protests from exile, urging demonstrators this week to keep the movement "disciplined" and "as large as possible."

The crown prince called for Iranians to chant together against the country's leadership at 8 p.m. local time, or 12 p.m. Eastern, on Thursday and Friday, and many did seem to answer his call.

Pahlavi's call to action "could be a turning point" in the protest movement, Yacoubian told CBS News on Thursday.

"This is a regime that is not afraid to use lethal force," Yacoubian said. "But the question is, to what extent, if they become overwhelmed, if the protests become overwhelmingly large and if there are elements in security forces, police, and so forth, kind of at that local level, who themselves are suffering the effects of this economic crisis and who decide not to shoot at people: These are the kinds of questions I think that we need to watch."