Why are there protests in Iran and what has Trump said about US action?

Hundreds of people are believed to have been killed in Iran as days of large protests threaten the future of the ruling regime. Thousands more have reportedly been arrested.

Donald Trump has also repeatedly threatened military action if security forces kill protesters.

On 28 December shopkeepers took to the streets of Tehran to express their anger at another sharp fall in the value of the Iranian currency, the rial, against the US dollar on the open market.

The rial has sunk to a record low over the past year and inflation has soared to 40% which has resulted in crippling price rises for everyday items like cooking oil and meat. Sanctions over Iran's nuclear programme have squeezed an economy also weakened by government mismanagement and corruption.

University students soon joined the protests and the demonstrations began spreading to other cities. There were wider calls for political change, with crowds frequently heard chanting slogans against the country's Supreme Leader, Ayatollah Ali Khamenei.

Expressions of support for Reza Pahlavi, the exiled son of Iran's late former shah, became more widespread towards the end of last week, when thousands of people took to the streets of Tehran and other major cities.

According to the US-based Iranian Human Rights Activists News Agency, protests have been confirmed in 186 cities and towns in all 31 of Iran's provinces since the start of the unrest. It has not provided an estimate on the number of people believed to have taken part in them, although it has said more than 10,000 protesters have been arrested.

Authorities have cracked down hard. A range of weapons, from water cannon to live ammunition, have been reportedly used against protesters to deadly effect. Several people who spoke to the BBC in the capital Tehran said the response to protests in the past week has been intense. Medics have described hospitals as "overwhelmed" with dead and injured.

Iran's judiciary chief has vowed "swift and harsh" punishment, warning courts to show no leniency towards "rioters".

US-based rights group the Human Rights Activist News Agency (HRANA) reports nearly 500 protesters and 48 security personnel have been killed since protests began. Among those reportedly killed are Amir Mohammad Koohkan, 26, who was a football coach and Aminian, 23, a Kurdish fashion student.

BBC Verify has reviewed a clip from a funeral in Tehran that shows mourners chanting "Death to Khamenei" - the Supreme Leader of Iran.

The country is shrouded in an internet blackout, which experts say began on Thursday. Elon Musk's Starlink satellite network is being touted as one way to connect to the world, but users have been warned such connections could be traced by authorities.

On Monday, Iran's Foreign Minister Abbas Araqchi claimed security forces have brought anti-government protests under total control. According to state TV, supporters of the authorities took to the streets in solidarity against recent "terrorist actions".

The government has also announced three days of mourning for what it called "martyrs" killed in a "national battle against the US and Israel" - two countries that Tehran says are fomenting unrest.

Iran, a major power in the Middle East, is ruled by a Supreme Leader, Ayatollah Ali Khamenei, with a population of around 90 million.

It has a parliament but this is heavily influenced by MPs loyal to Khamenei, who has the final say on the most important matters – including how to deal with the protests.

Iran was a key Western ally until 1979, when the shah (king) was overthrown in an Islamic revolution and a devout Shia Muslim regime took over. Since then the country has been run along strict religious lines. Criticism of the regime is not tolerated and personal freedoms have been heavily restricted.

A law requiring women to wear headscarves has been a particular source of deep resentment – and fuelled mass protests in 2022. Iran has one of the highest execution rates in the world and is consistently ranked among the worst human rights offenders.

Western countries have had strained relations with Iran since the revolution, with the US and Iran becoming major adversaries.

Washington accuses Iran of destabilising the Middle East, especially through its support of armed groups, including Hamas in Gaza, Hezbollah in Lebanon and the Houthis in Yemen.

For its part Iran accuses the US of interfering in the region.

The US has been a leading opponent of Iran's nuclear programme, claiming it aims to build a bomb – something Iran denies. It bombed Iran's nuclear sites last year, while international sanctions on Iran over its nuclear activities have had a drastic effect on Iran's economy.

Donald Trump and his administration have threatened "very strong options" to intervene in Iran, which could include armed action.

Speaking to journalists on Sunday night, the US president said Tehran had called him to "negotiate" but warned he may have to act before a meeting could be set up.

A US official told the BBC's US news partner CBS that Trump has been briefed on options for military strikes on Iran.

Trump has not yet elaborated on what US plans are, but on Sunday said Iranian leaders "want to negotiate", because "they are tired of being beat up by the United States".

The Wall Street Journal reported that other options available to Trump could include boosting anti-government voices online, imposing further sanctions, or using cyber-weapons against Iran's military.

Iran's Foreign Minister Abbas Araghchi warned the country is fully prepared for war if attacked.

Iran restricts international news organisations like the BBC from operating inside the country. The state broadcaster and official agencies follow strict guidelines dictated by the state. Independent Iranian journalists routinely face persecution and harassment for any reporting that is critical of the authorities.

Internet access is also heavily restricted, with most of the major social media platforms and Western news agencies banned. However, Iranians have become adept at using a variety of methods such as VPNs to circumvent these restrictions.

But the ongoing blackout has almost completely cut off Iranians from the outside world. Phone connections no longer work as well.

Until the blackout came into force on Thursday evening, hundreds of videos from the protests were posted on social media. Iranians regularly spoke to foreign-based journalists to provide eyewitness accounts of the protests.

Since then, the flow of videos has been significantly reduced, and it has become extremely difficult to speak to people inside.

A minority of Iranians have access to SpaceX's Starlink, and have been posting a few videos of the latest developments.

Some have also managed to momentarily connect to the internet and share their observations with journalists, friends and family members living abroad.