Forget the debate on the economy — Brexit is a huge risk to our security

The Brexit debate has been monopolised by the future trade and customs relationship. But another vital issue is now looming: the impact on Britain’s security, just at a time when President Trump is casting doubt on the US commitment to Nato.

I suspect that the reason security has not so far had much airtime in the negotiations is that ministers assumed it would be fairly straightforward. After all, the EU has as much interest as Britain in working together against shared threats from terrorism, organised crime and cyber attacks.

As a former National Security Adviser, I know how highly security professionals around Europe rate the contribution of our world-class intelligence agencies and police forces. Just this week, the head of one of those agencies, Jeffrey Fleming of GCHQ, revealed that Britain had played a critical role over the past year in disrupting terrorist operations in at least four European countries.

Brexit shouldn’t be a problem for intelligence co-operation, which happens outside the EU. But intel tip-offs need to be followed up by police action to disrupt plots and arrest suspects, and then by prosecutions. Since terrorists and other criminals are no respecters of national borders, the EU has developed a whole toolkit to enable rapid cross-border co-operation by the law enforcers.

This covers such things as databases of fingerprints and DNA, an alerting system, police co-operation through Europol and the European Arrest Warrant (EAW), which has hugely speeded up sending back criminals wanted for trial elsewhere in the EU.

Britain is one of the biggest users of these measures. For example, a senior police officer told a Lords committee recently that UK police had accessed the alerting system a staggering 539 million times in 2017. Under the EAW, the UK sends back around 2,000 criminals to other EU members, and takes 200 or so for trial here. This network of co-operation helps keep us all safe.

The Prime Minister has made an unconditional commitment to European security, and proposed an EU-UK treaty to maintain current levels of co-operation after Britain leaves. So what’s the problem?

There are two, actually: the EU approach and the clock.

Michel Barnier, the EU’s negotiator, has regularly poured cold water on the idea that Britain could have the same level of operational co-operation once we become in EU parlance a “third country”. He said it again this week, emphasising that while the EU would want to work closely with Britain, our decision to leave had consequences: as a third country, Britain wouldn’t be able to use the EAW system, or have full access to all the databases and networks.

It’s true that there is no precedent for a third country to be closely involved with the whole range of EU security instruments. Some require the third country to accept jurisdiction of the European Court of Justice, which would cross one of the Prime Minister’s remaining red lines. And the EAW seems to be out of bounds unless Britain accepts free movement of people: another red line.

So the EU vision is that the UK would have some level of access, but less than an EU member, meaning that co-operation would become slower and more cumbersome. And Britain would not be able to influence how EU law and practice developed after we had left.

British ministers clearly hoped that the strength of our security contribution would override legalistic EU objections. I agree there is a strong case that a comprehensive treaty would make both Britain and EU countries safer. The problem is that I don’t think the EU will buy it. For them, there is a principle at stake that third countries cannot have the same rights as members.

They may be bluffing. But the experience of the Galileo satellite programme doesn’t bode well. Here too, Britain had a powerful case for staying in a project that we had played a major role in developing. But the rule book said third countries couldn’t be fully involved, so Britain hasn’t been allowed to compete for contracts.

That raises the second problem, the clock. Assuming there is a transition agreement, Britain will be able to maintain full security co-operation with the EU until the end of 2020. But that leaves alarmingly little time to negotiate a complex and unprecedented treaty, even if the EU were willing.

If that idea isn’t going to fly, then Britain will need a plan B, presumably a patchwork of ad hoc agreements. But they too could take years to negotiate. Perhaps the transition period will have to be extended until new arrangements are ready. Whatever the solution, it is imperative that Britain doesn’t fall off a security co-operation cliff-edge at the end of 2020.

There are also question marks over how Britain will work with the EU on defence issues, but these are less central to our national security. Nato remains the heart of our defence interests, and will become even more important to us after Brexit.

But here too, all is not well. As a candidate, President Trump questioned the value of Nato. As President, he hesitated about renewing the US commitment to the crucial mutual defence commitment. He is on the warpath about low defence spending by many European members, linking this to the issue of trade surpluses.

If there is a bust-up at next month’s Nato summit as there was at the recent G7, there could be real damage to the mutual trust built up patiently over two generations and on which Nato depends.

In a world of many threats, this level of uncertainty about our core defence and security interests is deeply troubling.

• Lord Ricketts is a former National Security Adviser and a former Ambassador to Paris