Brexit raises questions for EU defence integration

At the moment Brussels expects to engage with London on the same basis as with other third countries.

However, given its capabilities in this area, it is not unreasonable for the UK to expect a role proportional to its security contributions, and without these contributions the EU's plans for 'strategic autonomy' are unlikely to be credible.

Since the 2016 referendum (and perhaps as a consequence of the result), the EU has shown interest in greater integration in this area, which the UK often blocked with its veto.

In 2017, the Permanent Structured Cooperation (PESCO) was launched, with the goal to develop joint military capabilities and operational capacity.

The European Defence Fund (EDF), proposed by the Commission to help member states coordinate their defence spending, is due to be granted approximately €13bn from the next long-term budget (Multi-Annual Financial Framework, MFF).

While it is an exaggeration to speak of an 'European army', in recent years there has been an increased movement towards further integration on defence.

Incoming Commission president Ursula von der Leyen has made "an integrated and comprehensive approach to [European] security" a priority of her programme, while suggesting strengthening institutions such as the European Defence Fund (EDF) and using qualified majority voting (QMV) in foreign policy.

Space frontier

The new Commission will also include a new directorate-general for defence industry and space, responsible for an "open and competitive European defence equipment market" and implementing space programmes.

French president Emmanuel Macron, who recently displayed his ambitions to be Europe's leading diplomat, has also been calling for a stronger role for the EU on the international stage.

In his call for European renewal, he argued for a treaty on defence and security, increased spending and setting up a new institution, the European Security Council, for more effective decision-making.

Macron has stated multiple times that reinforcing European defence integration was a priority for his government, while also reiterating his commitment to cooperation with the trans-Atlantic alliance.

After the G7 in August, Macron hosted ambassadors based in France and made a speech about the importance of building 'European sovereignty' in the wake of global changes, warning that Europe could become a minor actor in world dominated by the US and China.

Part of building this European autonomy, according to Macron, is to be "sovereign in the sphere of defence," and he pointed out that this cannot be built without the UK's participation.

Minus the UK

But neither the commission nor the 27 capitals have set out in detail their vision for future coordination and cooperation with the UK after it is no longer part of EU institutions.

The UK is one of the two major military players on the European continent, and as Macron recognised, without its involvement, European defence initiatives are unlikely to be credible enough to match the ambition of developing a more autonomous defence policy.

The European Court of Auditors pointed out that the EU's planned increase in defence spending would not compensate for the gap created by the UK's withdrawal, and there would be a "mismatch" between resources and ambitions of European 'strategic autonomy'.

Although British contributions to the EU's Common Security and Defence Policy (CSDP) missions have not been significant, after Brexit the UK's strategic interests on the European continent will not change radically, and both Theresa May and Boris Johnson have stated their intentions to remain committed to European security.

For future arrangements, much will depend on the political ambitions and level of trust between both sides, whatever the outcome of Brexit.

Even in a no-deal scenario, the UK could be willing to contribute and participate in operations that are in its strategic interests, notably those in the EU's neighbourhood.

The EU seems keen to welcome the contribution of UK assets for its objectives, but at the same time it is not prepare to go further than current arrangements with third parties for defence cooperation.

It is not clear yet how countries outside the EU could engage with PESCO, for instance, but they are unlikely to get any influential role.

Brussels' current vision for cooperation on defence, where third countries can contribute but have no say in decision-making and in the guidance of operations, is unlikely to be attractive to the UK.

Most of the defence sphere is not about the EU framework – the Commission itself admits that NATO will remain the cornerstone of European security, and the alliance with the US will likely remain the UK's preferred choice.

Cooperation could also continue via bilateral agreements, notably the defence treaty with France, as well as the new European Intervention Initiative (EII) set up by Macron, of which the UK is already a member.

Overall, both sides have a number of questions to answer about their future security and defence relations.

The UK will have to develop a policy towards the EU's integration initiatives (whatever path these take), and to set out its preferred formats for future dialogue.

Meanwhile, the EU appears to have given little thought about how to cooperate with the UK on a joint basis, rather than sticking to its previous formats of cooperation.