In a basement beneath the Strand in London, just metres from the cafes of Somerset House, two academics sit hunched over their laptops.

One routinely perches himself on a bright pink exercise ball, the other opts for a rickety office chair. Over days, weeks and months they have used their computer screens as a portal into one of the bloodiest conflicts of the modern age in what they say is an effort to understand, engage and give a voice to those young men who choose to leave the western democracies they call home to join the insurgents in Syria fighting the Assad regime.

In this war perhaps more than any other, these young men are exploiting the immediacy and worldwide reach of social media, smartphone apps and Skype to converse, share experiences, recruit would-be fighters and raise money from home with amateur propaganda posters and videos.

For the past year and a half, Shiraz Maher and Joseph Carter, from the International Centre for the Study of Radicalisation and Political Violence, have been gathering, analysing and sifting the information while also engaging directly with the increasing numbers of foreigners from countries including the UK, Belgium, France, Germany, Scandinavia and Australia who have travelled to Syria and apparently joined the jihadi fighting groups Isis and the al-Nusra front.

Research from the King's College-based ICSR in December estimated 1,900 people from western Europe had travelled to Syria to fight, including up to 296 from Belgium, 249 from Germany, 412 from France and 366 from the UK.

There is a touch of Four Lions, the UK comedy about young British Muslims waging jihad, to the images and posts gathered and analysed by the academics: from pictures of Kalashnikov-waving youths sitting on top of tanks and messing about in swimming pools to posts displaying the few home luxuries they still enjoy – Kellogg's Crunchy Nut Corn Flakes, Nutella and Haribos – the supply of which has led to this conflict being called the "five-star jihad" by British fighters.

But behind the undoubted posturing of young men who have been given guns, the communications of the British fighters in Syria on Twitter, Facebook, Tumblr, AskFM, and apps such as Whatsapp and Kik, provide what Maher says is an unprecedented insight into the motivation and activities of those who are causing the security services and the police in the UK such concerns.

It was in 2012 that the ICSR began analysing, observing and engaging with the foreign insurgents who, evidence suggested, were increasingly crossing the Turkish border to join the fighting.

Professor Peter Neumann, director of the ICSR, said: "One thing we had done in the past was to take an interest in what we can learn from the presence of extremists on social media. What we discovered was that the foreign fighters who started to join the insurgency in 2012 were all on social media and the idea was to bring it all together."

The centre has traced young British men – and a handful of young women – from cities including Bradford, Manchester, London, Birmingham and Portsmouth and the town of Crawley, who are in Syria with jihadi groups.

Maher has built relationships with some of those he speaks to regularly. "We have been very pleased at the level of access we have managed to get," he said.

He is aware that some of what is being said has to be treated with caution. But he believes he can trust the vast majority of the information he is gathering.

"I think it is important to give these individuals a voice," he said. "It is important that we understand them and get away from the hysteria that can surround this subject."

The access is two-way: social media has kept those who have joined the jihad in Syria in close contact with what is going on in the UK.

"They are very well-connected to what is happening here," said Maher. An article by George Monbiot in the Guardian comparing the jihadi fighters to foreigners who fought in the Spanish civil war, for example, was quickly picked up by British jihadis in Syria, according to the ICSR.

Maher and his team have been able to break news of the deaths of some of the estimated 10 British fighters killed in Syria. When Crawley-born Abdul Waheed Majeed drove a truck bomb into the gates of Aleppo prison in a suicide attack, Maher was texted at 5am with information about his death from a Briton in Syria.

The death of one of those he was in regular contact with seems more personal for Maher than others. Iftikhar Jaman, 23, was privately educated and had worked in a call centre in Portsmouth before travelling to Syria to join Isis, one of the deadliest jihadi groups involved in the fighting. Maher described him as a pious man driven by a humanitarian motivation to fight jihad in order to help the Syrian people.

When he died last December, his image adorned many propaganda posters disseminated via social media by British fighters in Syria. One carrying Iftikhar's picture read: "A man leaves his home to fight for the oppressed people … sounds heroic until you add in 'Muslim man'. Then he's a terrorist."

Maher believes understanding the motivations of the young British men who are radicalised or driven by humanitarian motives to travel to Syria and pick up a gun, is essential. "The vast majority of those who return will not be a problem here.

"So we need to support and understand them when they come back, many with psychological problems and post-traumatic stress."

However, the team accepts the assessment of the police and security services that there is a risk of "blowback" – the threat by some of the foreign fighters who return to their homeland. It is this apparent threat that has led to a spike in the number of people arrested in the first quarter of this year on terrorism-related offences for attempting to travel to Syria or on their return. There have been about 30 arrests in the UK to date.

"There will be a minority of people coming back who are brutalised and radicalised and have acquired very good terrorist skills, who can produce explosive devices, and who know how to handle weapons," said Neumann. "It is this minority who could become engaged in terrorist offences back here."

• This article was amended on 21 April 2014. An earlier version said Four Lions was about young British Muslims waging jihad in Afghanistan. Their target was the London marathon.