The claim

“What we’re facing in Iraq now with Isis is a greater and deeper threat to our security than we have known before.”

David Cameron, 29 August 2014

The background

Is the rise of the Islamic State the biggest threat to the UK’s security and safety in the history of the country? This is what the Prime Minister implied last year, when he upgraded the threat level in the UK from “substantial” to “severe”.

In the speech, he said: “With Isis we are facing a terrorist organisation not being hosted in the country but seeking to establish and then violently expand its own terrorist state. We could be facing a terrorist state on the shores of the Mediterranean bordering a Nato State.

“We are in the middle of a generational struggle against a poisonous and extremist ideology that I believe we will be fighting for years if not decades.”

As defence secretary Michael Fallon urges MPs to consider sanctioning air strikes on Isis fighters in Syria, we look at whether the Prime Minister is right about the group the biggest terrorist threat to Britons.

How many Brits have been killed in terrorist attacks in recent years?

Last week, 30 Britons were killed in Tunisia by a gunman who trained at an IS-affiliated camp in Libya. But this is quite an unusual – while Britons have been caught up in terrorist atrocities elsewhere, it’s not a regular occurrence.

David Anderson QC, the Independent Reviewer of Terrorism Legislation, has compiled annual reports since 2005 about the nature and scale of terrorist attacks, particularly those that impact on Britons.

The latest report was published last year and looks at terrorism in 2013 so it’s a couple of years out of date, but nonetheless provides useful context. From 2005 to 2013, 38 Britons were killed in terrorist attacks abroad. These attacks happened mostly in the Middle East and Africa. The worst was in Egypt in 2005, when eleven Britons were killed in the Sharm el-Sheikh attacks

Terrorists at home

Back in the UK, the picture is more optimistic. The London bombings of 7/7, tragically, killed 52 innocent commuters in 2005. But after that, the report says, we hadn’t seen an Islamist terrorist attack claim any lives in this country until 2013, when Lee Rigby was killed in Woolwich.

That isn’t quite the full story, though. That only counts Islamist terrorist attacks here, not attacks motivated for other reasons or perpetrated by other groups. For instance, the Real IRA claimed responsibility for the killing of two soldiers at Massereene Barracks in Northern Ireland just 6 years ago.

In Birmingham, Ukrainian student Pavlo Lapshyn attempted to “start a race war” by setting off bombs in three mosques in the West Midlands. Additionally, the attack on Glasgow International Airport in 2007 could be defined as an attempted terrorist attack – nobody was killed – but it was carried out by Islamists.

In the 2013 report on terrorist acts, Anderson writes: “Islamist terrorism has never been a major cause of mortality in the UK or in other western countries; but it maintains the capacity to spread fear and alarm.” This suggests that the ‘threat’ is more about causing fear than causing harm on a large scale.

As for the terrorist plots that don’t succeed, there aren’t that many of them either. In November 2013, Andrew Parker, Director General of MI5, was widely reported as stating that 34 terrorist plots had been foiled since the 7/7 bombings. That means roughly 3-4 each year. But the Director-General had previously stated that one or two serious terrorist plots are typically seen each year, and this is a safe number to assume.

Such plots include the one of Erol Incedal, who has faced two trials – the latest in March this year – for preparing for acts of terrorism. We don’t know a lot about the case because it’s been shrouded in secrecy. But we do know that he praised Isis commanders and talked about being in Syria’s mountains, so could have been connected to them or at least wanted to be.

Past attacks – the IRA

From the late 60s to 2001, the UK faced threats at home from the Irish Republican Army (IRA). The militant organisation was founded by Irish nationalists with the aim of uniting Ireland and making it independent.

Ulster University maintains a Conflict Archive on the Internet (CAIN) which documents conflict in Northern Ireland across the last four decades.

There were 36,000 shooting incidents and over 10,000 bomb explosions, according to the database. Over the course of 33 years, more than 3,500 people were killed, 1,707 by the IRA.

The global perspective

A report published by the Institute for Economics and Peace a few months ago found that since 2000, there has been over a five-fold increase in the number of people killed by terrorism globally. The most deadly terrorist organisations, according to the Institute, are the Taliban, Al-Qaeda, Boko Haram, and then Isis.

Isis is the second largest of the four groups, with an estimated 20-30,500 fighters. The Taliban has nearly double.

Worryingly, though, trends of deaths caused by these organisations over the last thirteen years show that Isis caused more deaths in the last 4 years than any of the others. Although it’s a relatively new organisation, clearly its strength is growing and as they gain control they are more likely to have the capacity to cause devastation abroad.

We’ve already seen terrorist attacks carried out by militant Islamists closer to home. Earlier this year police in France killed three Islamist militants after they massacred 12 staff working at satirical magazine Charlie Hebdo. The two brothers who carried out the attack had previously been involved in a network helping to send would-be jihadists to fight for al-Qaeda. They had also been imprisoned for terrorist activities. Cherif Kouachi in 2005 as he was about to board a plane to Syria, and again in 2008. His brother Said was imprisoned in 2001 for plotting to bomb the US embassy in Paris. A third gunman, Amedy Coulibaly, held hostages and killed four people in a Jewish supermarket in Paris on the same day. He was also an Islamic extremist and believed to be connected to the brothers.

The verdict

The answer is, judging by past experience, Isis have so far not managed to cause devastation and loss of life – over here – on the same scale as the IRA did in the 70s and 80s. It’s therefore difficult to stand up the claim that they are a ‘greater and deeper threat’ to the UK than any we’ve seen before.

However, looking forward, this could well change.

Judging from global reports on terrorism, it’s clear that Isis’s strength is growing and they are causing more and more damage across the Middle East and branching out elsewhere. Generally, Britons don’t travel to those countries that are worst affected by Isis and similar terrorist organisations, so the chances of being killed in an attack is extremely low.

But as more fighters come back to the UK from Syria and other parts of the Middle East where Isis is operating, it’s possible that we could face more terrorist attacks at home from them, and they could well be the defining ‘threat’ of this generation.

By Sophie Warnes