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An EU that did not have the UK as a core component of its counter-terrorism and security efforts would arguably be much weaker, leaving the UK facing greater risks.

The debate about whether the United Kingdom will be better off in or out of the European Union is driven more by emotion than by rational analysis. To the extent that rationality has played a role, it has applied to the question of which option will leave the British people economically more prosperous. But claims have also been made, by exponents of both camps, that the UK will be more or less secure outside of the EU. As with much of the ‘Brexit’ debate, such claims have been made with little in the way of factual substantiation, and the issue is, like so much else about the UK, complicated by the depth and breadth of the country’s global engagement.

The first, and obvious, question to ask is: secure against what? Since the British government began publicising national-security strategies in 2008, these have been based on the presumption that the UK no longer faces an existential military threat of the kind it faced during the Cold War. Threats to the UK are a function of the country’s unique exposure to the currents of globalisation – something that neither the ‘in’ nor the ‘out’ camp claims to want to change – and are largely non-military in nature. The most recent iteration of the strategy document emphasises the role of uncertainty, which makes specific threat prediction a difficult exercise. But there are some obvious threats, notably that from transnational jihadist terrorist groups, which seem to have a generational character and can perhaps serve as a benchmark to test the claims of the pro- and anti-Brexit campaigns.

What will the Americans think?

One claim that has gained currency is that the UK is an intelligence superpower which benefits hugely from its traditional intelligence links with the United States, via the UK–US intelligence-sharing and -cooperation arrangement (UKUSA) and, by extension, its membership of the ‘Five Eyes’ alliance of Anglo-Saxon nations. Europe, by contrast, is relatively weak in this area. At British insistence, the Lisbon Treaty made explicitly clear that Europe has no competence in matters of intelligence and security which, under the rubric of national security, remain the preserve of nation-states. And individual European states typically have far less in the way of intelligence capabilities than the UK. Only two other states, France and Germany, have intelligence services with a claim to truly global reach, and the capability and reach of neither country matches that of the UK. Whatever happens in the forthcoming referendum, Europe will continue to have an interest in intelligence cooperation with the UK. But in the event of Brexit, the terms of trade will necessarily be different – and not necessarily to the UK’s advantage.

Take first the intelligence relationship between the UK and US, a key part of the so-called special relationship (a term intelligence professionals on both sides of the Atlantic seldom, if ever, use). This relationship is based on a shared culture, and a shared historical experience dating back to the Second World War. It involves an unprecedented degree of sharing and cooperation, and the existence of a no-spying agreement, something Germany tried and failed to secure as part of the fallout from the Snowden revelations. But in the final analysis this relationship is highly transactional, a function of the equities both parties bring to the table. There are no free lunches in the intelligence world, and cultural affinity is no substitute for performance. And while the signals-intelligence element of transatlantic cooperation has proven remarkably consistent and durable, on the human-intelligence side the relationship has been much more volatile, and at times almost antagonistic.

Although it may not always have been the case, it is now clear that the US government, including the US intelligence community, sees the value of the UK as deriving at least in part from its membership of the European Union. During his April 2016 state visit to the UK, President Barack Obama stated that Brexit would not harm US–UK intelligence cooperation.1 But in the event of Brexit, the US intelligence community would, rightly or wrongly, see the UK as a diminishing asset, less well placed to assist the US in its own intelligence relations with Europe over issues such as the spreading of best practice. Intelligence cooperation will not cease if the UK leaves the EU: in the short term, there may be little perceptible change. But in the medium to long term, the UK as an independent player is likely to have to work harder to demonstrate its continuing relevance. Under President Obama, the US intelligence community has withdrawn from the role it previously played against al-Qaeda, in which it directed a global intelligence web, acting as counter-terrorism-intelligence collector for the Western liberal democracies. The emphasis now is less on unilateral American action, and more on working through allies and partners – who are expected to pull their weight.

European cooperation

UK intelligence relations with European countries have until recently been almost entirely bilateral and subject to wide variation depending on the capabilities and priorities of the services involved. When it comes to counter-terrorism, European states suffer from a number of weaknesses which, if not absent in the UK, are notably less pervasive there. These include a lack of expertise in languages such as Arabic and a lack of engagement with Islamic communities which hinders the ability to develop human-intelligence sources.

One consideration shared by the UK and other European services is the growing scale of the terrorist problem and its evolving character. During the preceding decade, the main threat came from al-Qaeda-linked terrorists, focused almost exclusively on replicating bomb plots on the scale of 9/11, and mainly operating under direction from al-Qaeda controllers located around the Pakistan–Afghanistan border. Few of the aspirant terrorists had received much, if any, training, and many were not especially intelligent. All these factors made the investigation of terrorist plots relatively easy to undertake – though it should be emphasised that there is no such thing as an easy counter-terrorism operation. It still took time to get to grips with the nature of the threat, and to know where to look. But by the time of Osama bin Laden’s death in 2011, there was a sense that Western intelligence had a grasp of the problem – even if this owed much to intelligence-led drone strikes against al-Qaeda leaders in the tribal areas, which robbed the group of the ability to plan and orchestrate attacks in the West.

The new terrorism threat from the Islamic State (also known as ISIS or ISIL) is of a different order. To begin with, there are many more young Europeans who have gone to Syria to fight with ISIS than went to join al-Qaeda. Those who have returned to their home countries – some 20–30% – are trained, battle-hardened and radicalised.2 Of course, not all returnees are in this category: some come back frightened and disillusioned, and want nothing further to do with ISIS or terrorism. But that still leaves a significant number of jihadists who pose a potential threat, and it is now clear that ISIS sees operations in Europe as the third leg of its strategy, along with the development of the caliphate in Syria and Iraq, and the activities of affiliated jihadist groups in other Islamic states. The sheer numbers involved pose a challenge for even the most proficient intelligence and security services. The terrorists have also switched tactics away from bombings, which are difficult to pull off, in favour of the kind of mass shootings witnessed in Paris in 2015, which are much easier, and are guaranteed to generate significant casualties and publicity. While such operations may have a measure of strategic direction, the groups undertaking them appear to enjoy significant operational autonomy. The Paris attacks were a multi-phase operation involving separate logistics and support units, and were conducted amid high levels of communications security, making them hard to detect.

When it comes to counter-terrorism operations, many European countries have difficulty integrating the work of their intelligence and security agencies with that of the police. Political elites and judiciaries are distrustful of intelligence, and in many European countries politicians have failed to take effective ownership of their intelligence communities. By comparison, the UK model of counter-terrorism combines the two functions effectively. The intelligence agencies and the police share the same agenda and the same databases. For day-to-day activities, MI5 – the UK’s internal-security service – has primacy. But when a specific investigation begins, it takes place under the direction of a police senior investigating officer (SIO) who has a remit to gather evidence that will lead to criminal convictions. In such investigations, an important function of intelligence is to help the police to find such evidence – an approach that many European judiciaries would find unacceptable. But if future terrorist atrocities are to be minimised, the case must be made for a wider European adoption of the UK approach. The Franco-Belgian investigative follow-up to the Paris attacks was an impressive piece of work, and it is now known that the jihadists launched an assault in Brussels because they felt the net closing in on them much faster than expected.3 In order to be really valuable, however, this kind of investigation needs to take place before, not after, the fact.

The news in Europe is not all bad. European services are having to adapt and improve in the face of a much more serious threat than had previously been envisaged. Intelligence sharing is getting better, and this is particularly true of large datasets, which are becoming increasingly important in identifying individuals likely to pose a security threat. Access to this data is highly valued by the UK intelligence community. Brexit would result in the UK being denied access to these datasets, at least until a series of bilateral data-sharing agreements with European states could be concluded. Moreover, it should not be forgotten that some European services have expertise and presence in parts of the Islamic world, notably North Africa and the Sahel, that the UK cannot match. And operational cooperation has moved to a new level, with plans to create an ISIS task force involving those European states most affected by the problem.

Domestic concerns

It has been alleged that Brexit would free the UK from restrictions imposed by the European Convention on Human Rights (ECHR) and the jurisdiction of the European Court of Justice (ECJ). The former is not, in fact, an EU institution. The ECHR was drafted in the early 1950s under the aegis of the Council of Europe, and the UK played a leading role in bringing the convention into being, with the aim of ensuring that the excesses of Nazi Germany could not be repeated. There is no evidence to suggest that the UK intelligence community feels inhibited by having to conform to the provisions of the ECHR or wishes to obtain an exemption from these provisions. To the extent that the convention presents a problem for the UK, this arguably derives from the decision by the government of Tony Blair to incorporate the ECHR into UK law, thus requiring all UK legislation to be ECHR-compliant. As Vernon Bogdanor has pointed out, this decision potentially sets a Parliament that is supposedly sovereign, and hence in principle entitled to make whatever law it likes, at odds with a judiciary that may refuse to implement legislation deemed not to be ECHR-compliant.4 But that outcome was the result of a sovereign UK decision, not a demand from Brussels. The ECJ – which is an EU institution – does have some potential to damage UK security if, in respect of several cases brought before it as a consequence of the Snowden revelations, it judges that GCHQ’s bulk-intercept operations are disproportionate and hence unlawful. Such a decision would substantially weaken UK – and by extension European – intelligence, and particularly counter-terrorism capabilities, and it is hard to imagine any UK government readily accepting such a judgement. In that respect, Brexit could be seen as providing some benefit. It is still far from being a foregone conclusion, however, that the ECJ will find against the UK.

On the issue of border security, the Brexit camp has claimed that by leaving the EU the UK will regain control of its borders.5 It is not obvious how such a claim can be substantiated. The UK is not part of the Schengen Agreement, can screen EU nationals entering the UK, and has the right to refuse those where the evidence suggests their presence would not be conducive to the public good.6 The issue is whether such evidence is available. It is possible to envisage a post-Brexit situation in which the nationals of all EU states were required to obtain visas before travelling to the UK, in which case those states would likely impose reciprocal requirements on UK nationals. It is hard to see the UK business community reacting with enthusiasm to such a development, nor does it seem compatible with the Brexit campaign’s vision of a free-trading UK. And absent a visa regime, it is difficult to see how security information about EU nationals posing a threat to the UK will be more readily forthcoming than it is now.

When it comes to non-EU nationals, it is unclear how EU membership poses an increased security risk to the UK. For some years now, the UK has sought to push its virtual borders as far out from its physical border as possible, using the e-Borders initiative, whereby visa applicants from countries of potential concern are screened in their own countries and can be screened again once they reach the UK. To the extent that ‘undesirables’ are let into the country, this is a consequence of insufficient investment in border-security resources, both men and machines. A further consideration in relation to border security is that a Brexit would very likely trigger another Scottish-independence referendum, which may well succeed. The result would be that the UK – or rather what was left of the UK – would have two additional hard borders to police, one with Scotland and one with the Republic of Ireland. Far from pushing Britain’s borders further out, Brexit would bring them to the front door.

In the final analysis, it is hard to argue that UK national security would suffer drastically in the event of Brexit, although it is possible to point to specific discontinuities that would impact adversely on security capabilities, at least in the short term. On the other hand, it is hard to identify any significant security advantage that the UK would derive from leaving the EU. Indeed, in the long term, an EU that did not have the UK as a core component of its counter-terrorism and security efforts would arguably be much weaker, and that, in turn, would leave the UK facing greater risks.


1 Colleen McCain and Jenny Gross, ‘Obama Urges U.K. to Remain in EU’, Wall Street Journal, 25 April 2016.

2 Soufan Group, ‘Foreign Fighters: An Updated Assessment of the Flow of Foreign Fighters into Syria and Iraq’, December 2015,

3 Aurelien Breeden, ‘Brussels Attackers’ Original Target Was France, Prosecutors Say’, New York Times, 10 April 2016.

4 Vernon Bogdanor, The New British Constitution (Oxford: Hart, 2009).

5 See, for example, Michael Gove, ‘Michael Gove Makes Case for EU Exit: “It’s Time to Take Back Control”’, Guardian, 19 April 2016,

6 EU Commission Free Movement Directive 2004/38/EC states that EU/EEA states may deport nationals of other EU/EEA states and issue exclusion orders against them on grounds of public policy, public security or public health.

Nigel Inkster is Director of Future Conflict and Cyber Security at the IISS. He previously served for 31 years in the British Secret Intelligence Service (SIS).

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Survival: Global Politics and Strategy

June-July 2016

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