Basij appeared on motorbikes at post-election demonstrations
By Jon Leyne
BBC News, Tehran correspondent
At any opposition demonstration in Iran they materialise from nowhere. For opposition supporters, they have become notorious.
The government's Basij militia have become President Mahmoud Ahmadinejad's chief enforcers, as he tries to consolidate power in the wake of his disputed re-election.
Sometimes they tear into demonstrations in fleets of motorcycles, wielding clubs, and sometimes firearms.
Sometimes they are in plain clothes, mingling amongst the crowd until it is time to strike.
It's like setting a wolf loose amongst a flock of sheep
Amir Farshad Ebrahimi Former Basiji
One notorious tactic is for them to wield tiny knives or razor blades to use against protestors from behind their backs.
Many are recruited at the age of 12 or younger. In their long training they are steeped in the ideology of the Islamic republic - indoctrinated, some would say.
Amir Farshad Ebrahimi was just such a young Basiji. He has long since left the militia and fled the country.
He describes the training as "brainwashing."
"I can genuinely say that it's a form of brainwashing," he told me.
"It takes place every night or weekly in the mosques they attend, so much so that they really believe that the protesters and opposition supporters on the streets are standing against the Prophet's teachings and Islam, they are mohareb (enemies of God) and their blood can be spilt, they should be killed."
He said that Basijis have been performing ritual ablutions, as if before going to the mosque, before going out to quell recent protests.
It is clear the Basij have been preparing to deal with this sort of internal unrest for many years, quite different from their role as frontline soldiers in the Iran-Iraq war.
Militia often mingled with crowds in plain clothes before striking
And it's a role which Mr Ebrahimi says many of them have taken to with enthusiasm.
"There is no need at all to tell them what to do - when they hand them a baton or gun and tell them to go, it's clear what they have to do.
"It's like setting a wolf loose amongst a flock of sheep," he said.
But there are also some Basijis who are having doubts, according to Mr Ebrahimi.
He says he has received 10 to 20 calls or emails from his former colleagues asking what they should be doing.
"Some of them have become disillusioned," he said.
"I can't tell you how many. But I am sure that many are not happy about what is happening right now.
"But others are standing firm, supporting their revolution, taking up arms and oppressing people. They don't even have any mercy for the injured.
"They even torture detainees in prison. It's a very complicated situation."
That analysis is supported by Alireza Nourizadeh, an expert on the Basij, and director of the Centre for Arab and Iranian Studies in London.
"These Basijis are also part of the nation and gradually you don't expect them to stay loyal to the authorities when they see that people in the streets are their neighbours and their children," he said.
"I heard that many, many of the Basijis, especially their commanders, when they go home they have problems with their children and their wives, and they ask 'why do you kill people?' "
By all accounts the Basijis are a mix of ideologues, some just in it for the power or the money, and some who relish the violence.
But the corps is underpinned by many true believers.
Some interviewed recently spoke about their belief that they were working for the improvement of humanity: "We want to change the world, to save the world and all its people from tyranny and submit only to God."
That ideology is a strength for the militia, but also a potential weakness.
As the conflict with the opposition drags on, as it seems set to do, the self doubts must surely creep in.
A crucial factor in the success of the Islamic revolution in 1979 was the defection of the armed forces from the shah.
Those who rule the Islamic Republic have worked hard to build up their own loyal cadre, made up of both the Basij and the regular forces of the Revolutionary Guards, to avoid any repeat of that collapse.
But in the ferment into which the country has been driven, even the loyalty of these ultra-loyalists may be open to question.
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