(CNN) - The largest public display of discontent in Iran since the 2009 Green Movement has resulted in 21 deaths and 450 arrests, restricted access to social media apps and brought pushback from the Iranian government. Such scenes might have been unfathomable a decade ago -- but for the sixth day, protesters are challenging the rule of Supreme Leader Ayatollah Ali Khamenei.
CNN spoke with experts about the ongoing unrest in the Islamic Republic of Iran.
Why is this happening?
The protests, which began Thursday night, are a reaction to Iran's sputtering economy, rampant corruption and rising fuel and food prices.
But something larger seems to be at play.
Iranians are angry, experts say, because they expected life to get better when severe sanctions were lifted after the deal in 2015 between the P5+1 and Iran over its nuclear program. The five permanent members of the UN Security Council -- the United States, the UK, Russia, China and France -- and Germany make up the P5+1.
While restrictions on financial, energy and transportation sectors were removed, hundreds of Iranian entities were not taken off the blacklists. And the United States has moved to create new sanctions over other violations, including a rocket launch this past summer.
Trita Parsi, president of the National Iranian American Council, and other experts say endemic economic mismanagement and corruption have left Iranians disenchanted.
Government policies have brought about higher unemployment and inflation. And there's a lack of sturdy international investment, Parsi added.
"The nuclear deal is overwhelmingly supported by the Iranian public, but there was an expectation that much more economic development would come out of it," Parsi said.
Is this just about bread and gas prices?
No. Years of political, economic and social grievances have driven some Iranians into the streets in the largest protests since 2009, said Reza Marashi, research director for the National Iranian American Council.
"Economic sanctions have exacerbated all of those Iranian-origin economic problems," he said.
"I don't think you can separate the economic from the political," he told CNN. "The government has an opportunity and a responsibility to address legitimate grievances that are being expressed."
Alireza Nader, a senior international analyst and Iran researcher at the Rand Corp. in Washington, said people have also lost trust in Iranian President Hassan Rouhani.
"The government is viewed as highly corrupt, increasing inequality is seen by the population as really a form of injustice," he said, adding "this was supposed to be a system that delivered justice to the people after the revolution of 1979 and it has failed."
Karim Sadjadpour, a senior fellow at the Carnegie Endowment for International Peace, said there's also a push to secure equal rights for women.
Nader said women in Iran have been fighting for decades for equal rights, but especially in the last few years, such efforts have become stronger.
"Women in Iran are highly educated. They are involved in the workforce, arguably more so than any other country in the Middle East, and they are continually suppressed. This is part of their fight to gain their freedom and their rights," he said.
An Iranian vice president said Saturday the government would work harder to resolve economic hardships.
Are these protests similar to those in 2009?
The new protests are intense, but so far they are nowhere as big as those in the Green Movement in which millions took part after accusations of widespread election fraud in 2009.
The National Iranian American Council's Marashi said today's demonstrations may be more of a civil rights movement than a revolutionary one.
There are other important distinctions. While the earlier protests primarily were in Tehran, had specific goals and an organized hierarchy of leadership, the current ones seem to challenge the rule of the Supreme Leader directly and have been seen across the country.
The exact origins of the protests are hard to pinpoint, but religious hardliners opposed to what they see as Rouhani's moderation are thought to have started them in Qom and Mashhad. They quickly spread to a wider section of the population focused on airing their economic grievances -- and more notably -- their dissatisfaction against Khamenei's rule.
"This is something that didn't happen in 2009. This is a huge thing to happen in Iran," said Nic Robertson, CNN's international diplomatic editor. "People don't say that publicly on the streets."
One resident told CNN of witnessing a protester tearing down a poster of Khamenei near Tehran University.
In his first remarks since the protests began, Khamenei on Tuesday accused Iran's enemies of "joining forces" and blamed them for inciting the protests.
Who are the protesters?
Many of the demonstrators are young Iranians fed up with the lack of economic opportunity.
Iran's unemployment rate among those 15 to 29 is well over 24%, according to official statistics -- and even higher among urban youth and women. The International Monetary Fund has called Iranian women an "untapped source of growth and productivity."
The protestors likely include some disillusioned Rouhani supporters, but they probably don't make up the bulk of the demonstrators, according to Parsi. Seven months ago, Rouhani won re-election with 57% of the vote (and 70% voter participation).
It's likely these protesters are people that typically stay away from traditional politics. Uncompromisingly anti-regime slogans suggest these demonstrators may belong to those who tend not to vote, don't believe the system can be reformed and either never subscribed to or have lost hope in gradual change, Parsi adds.
Other protesters are thought to include those who feel sidelined by economic desperation and humiliation.
How have global leaders responded?
President Donald Trump has been fiercely critical of the Iranian regime, prompting a tit for tat between him and Iranian leaders.
On Friday, Trump first tweeted, "The world is watching!" and that "oppressive regimes cannot endure forever." Trump said that Iran's leadership is squandering wealth to fund terrorism elsewhere.
On Monday, Rouhani said Trump has no right to sympathize with Iran because he has called the Iranian people "terrorists," according to Iran's semiofficial Tasnim News Agency. And on Sunday, state television broadcast Rouhani saying that Trump is "constantly creating problems" for Iranians, including with regard to visas and financial issues.
On Tuesday, the US leader continued his support for anti-government protests while lambasting deals negotiated in the wake of the Iran nuclear agreement under President Barack Obama.
Khamenei blamed Iran's "enemies" for stirring up unrest in the country, though he didn't mention Trump by name, while the secretary of Iran's Supreme National Security Council, Ali Shamkhani, accused the United States, UK and Saudi Arabia of using hashtags and social media campaigns inside Iran to incite riots.
British Prime Minister Theresa May's spokesman said Tuesday that the UK has called on Iran to engage in a "meaningful debate" on the issues the demonstrators have raised.
So what's the most helpful reaction?
Iranian-American analyst Holly Dagres said the best thing for the rest of the world to do is wait and see what happens next in Iran, where protesters have been heard on videos on social media chanting "Death to Rouhani."
"The fact that we are actually making statements that we think are in favor of the Iranian people, they are hurting them more than anything," she said.
Experts say that Trump's tweets are not helpful and that the world should show solidarity with the Iranian people by supporting freedom of expression.
Marashi said the protest movement "is of an Iranian origin and it will be of an Iranian ending."
Parsi said the protests are not a US issue. "This is not about Trump, and Trump stepping into this is not necessarily helpful, because he doesn't carry any credibility in Iran."
Comments against the Iranian regime may not only be unhelpful -- they may bring about a pretext for crackdowns, said Sadjadpour of the Carnegie Endowment for International Peace.
Iranian Foreign Ministry spokesman Bahram Qassemi said the Iranian people gave no credence to "opportunistic" remarks by Trump or his administration.
How is the story getting out?
As was the case in 2009, images and messages from citizen journalists are coming out via social media. Iranian authorities have restricted Instagram and Telegram, but users are accessing them with virtual private networks, or VPNs. The government controls the media and does not allow freedom of speech.
Without press access, the world is seeing what may be a skewed version of what's happening. "Independent verification of facts (is) hard to come by," CNN's Robertson said.
But images often are powerful.
In 2009, a video showing the last moments of protester Neda Agha-Soltan catapulted her into a symbol of the burgeoning reform movement in Iran. "That had a chilling impact on the protests in Iran, and it had a chilling impact around the world," Robertson said.
What's coming next?
The Green Movement lasted for months; this round of protests is less than a week old. It's unclear just how much dissent the government will allow.
Iran's Intelligence Ministry says so-called provocateurs will be targeted if anti-government protesters return to the streets.
"In 1979, Iranians experienced a revolution without democracy; today they aspire for democracy without a revolution," Sadjadpour said.
He said he believes a young Iranian society is seeking a more liberal, progressive nation but is unlikely to take up arms. Iranians are up against a government they know is willing to use force to keep power, he said.
"Despite the fact that many Iranians would have revolutionary ends, I don't think they are willing to pursue revolutionary means en masse the same way, for example, Syrians or Egyptians or others have over the last past five years in the Middle East."
But Sadjadpour also said that even if the protests are squashed -- as he expects -- it's not the end of dissatisfaction.
"The resentment toward the regime will remain and will eventually resurface in the future."
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