Thousands of Iranians have taken to the streets for more than a fortnight in protests against the country's government.
The death toll continues to climb as authorities attempt to stamp down on the unrest, prompting a warning from US President Donald Trump that the US could "come to [the] rescue".
Here's what to know about the situation.
What is happening?
Hundreds of mass protests have been occurring across Iran since December 28.
Just after 8pm on Thursday, the government shut down the internet and telephone networks, disconnecting Iran's 85 million people from the rest of the world.
Many Iranians have reportedly managed to skirt these restrictions by using Starlink and virtual private networks.
US-based human rights monitor Human Rights Activists News Agency (HRANA) estimates 2,500 have been killed.
Opposition network Iran International, which is based in London, says that the toll is as high as 12,000.
Roughly 18,434 people have been arrested, the HRANA reports.
Why did the protests start?
They were sparked by an economic crisis but have broadened into a movement demanding the end of the current government.
Economic pressure has intensified since September, when the United Nations brought back sanctions on Iran over its atomic program.
Iran's rial currency is in freefall and is now trading at more than 1.4 million to $US1 ($1.50).
In December, Iran introduced a new pricing tier for its nationally subsidised petrol, which raised the price of some of the world's cheapest gas.
Prices are up on meat, rice and other staples of the Iranian dinner table as the nation struggles with an annual inflation rate of some 40 per cent.
Food prices are expected to rise even further after the country's central bank decided to end a program that allowed some importers to access a subsidised US dollar-rial exchange rate.
In response to that move, some merchants closed shops and began protesting on December 28.
It did not take long for the demonstrations to explode into a wave of nationwide unrest.
Others who joined the protests have spoken of their anger over decades of corruption and mismanagement.
"This anger comes from the sense that the country has been abandoned, as if no-one intends to stop the collapse, the instability, or the soaring prices," Babak* (not their real name) told the ABC in early January.
"It feels like none of this matters to the ruling power, and no-one is making an effort to even acknowledge the lower-income groups who make up the majority of society.
"I hope this pressure continues until we reach an outcome because the bazaar has the power to break the back of this government and take it down."
Anger at the regime has been simmering for years, particularly since 22-year-old Mahsa Amini died in police custody in 2022.
Ms Amini was a student who was arrested in Tehran in September 2022 for allegedly violating Iran's hijab law.
Eyewitnesses say police then beat her, before she later died in hospital.
Iranian police denied involvement in her death, claiming she died from natural causes.
Her death ignited the Women, Life, Freedom movement, which quickly spread across Iran and demanded an end to female oppression.
In 2024, a UN Human Rights Council report concluded that her death was caused by physical violence inflicted by Iranian police.
How widespread are the protests?
Understanding the scale of the protests has been difficult for organisations that have set out to track them.
It is difficult for journalists to report on what happens inside Iran as there are strict rules around travelling into and around the country, as well as the threat of harassment or arrest by authorities.
Iranian state media has been providing little information about the protests, and online videos only offer brief, shaky glimpses of people in the streets.
The internet shutdown has further complicated the situation.
However, the US-based Human Rights Activists News Agency estimates more than 570 protests have taken place across all of Iran's 31 provinces in the last fortnight.
The Foundation for Defense of Democracies, a research institute also based in the US, estimates upwards of 750 protests have taken place in that same period.
Who runs Iran?
Iran has been a theocracy since 1979, when Ayatollah Ruhollah Khomeini led the Islamic Revolution.
Supreme Leader Ali Khamenei, Khomeini's successor, has spent more than three decades in power.
Before this it was run by the Iranian monarchy.
The Pahlavi dynasty came to power in 1925 and ruled for more than 50 years.
Mohammad Reza Pahlavi was their last king, who reigned from 1941-1979.
Many protesters in Iran have been calling for his exiled son, Reza Pahlavi, to return to power.
Reza Pahlavi, who is now 65 years old and living in the United States, has also encouraged the recent protesters in Iran, calling them "an opportunity to liberate that nation".
Will the US get involved?
US President Donald Trump has been trading barbs with top Iranian officials over the matter, suggesting the US may intervene if the situation continues to escalate.
The president wrote on his social media network Truth Social on January 2 that if Iran "violently kills peaceful protesters", the US "will come to their rescue".
"We are locked and loaded and ready to go," he said.
That threat took on a new meaning when, days later, American troops seized Venezuelan president Nicolás Maduro — a long-time ally of Tehran.
Mr Trump repeated that threat on Friday, saying Iranian authorities "better not start shooting, because we'll start shooting too", but ruled out putting US "boots on the ground".
This week, he promised Iranian protesters that "HELP IS ON ITS WAY", warning the Iranian government "will pay a big price".
Meanwhile, the regime has shifted from describing the protesters as "rioters" to branding them "terrorists", accusing them of taking action in an attempt to "please" the US.
The Institute for the Study of War says this suggests the regime has taken an "uncompromising stance" against the ongoing demonstrations to justify further crackdowns on the protests.
In response to Mr Trump's threats, Iranian Parliament Speaker Mohammad Bagher Ghalibaf warned that Iran could attack US military bases in the region or target Israel if the US attacks Iran.
ABC/AP
