The European Union’s Galileo network of satellites is the latest in a series of global satellite navigation systems providing precision data from space. America has had one since 1978, in the shape of the familiar GPS system. Russia has had one since 1982, and China since 2000. Galileo’s satellites have been circulating overhead since 2011 and the network is scheduled to be fully functional by 2020. Britain has been deeply involved in Galileo since the start, providing 12% of the overall costs, currently estimated at €10bn, and receiving about 15% of the work on the project. Now Britain’s participation is at risk.

Brexit is the cause of this, but for once Britain is not the only guilty party. The European commission and member states must share the blame for what is developing into an expensive squabble with very disturbing implications for post-Brexit relationships. The immediate argument is about Britain’s possible exclusion from the next phase of Galileo-related contracts. Already the Galileo back-up centre has been moved from Hampshire to Spain. Much more damagingly, the EU is proposing the UK’s long-term exclusion from the “public regulated service” part of the network. This is an encrypted service for the police, security and emergency services of EU member states. Britain has been deeply involved in its development and British agencies are anxious to participate in it when it is operational. Since January, however, the commission has argued that Britain should be excluded because the system’s integrity would be compromised if it were accessible to a non-EU state.

This is an absurdly bureaucratic and hostile stance to take towards a country that, Brexit or not, is and always will be an intimate European ally on all security issues. This newspaper holds no brief for Brexit or for Theresa May, but the prime minister has been clear that security cooperation with Europe must be fully maintained in spite of Brexit. She is right about that. But the EU’s short-sightedness may now be provoking an over-reaction in London. The chancellor, Philip Hammond, is said, in his frustration, to be trying to block the transfer of sensitive cryptographical expertise to French companies in the project and is threatening that the UK may go it alone with a separate satellite system, costing at least £5bn. As the Lib Dem peer Lord McNally said in the Lords recently, the Brexiters “did not put that on the side of the bus”.

It is hard to know how seriously to take all this. In the midst of so many other negotiations, the fate of the UK’s Galileo involvement is inevitably linked to other issues. Some entanglement is politically inevitable. Yet the fact remains, in spite of the Brexit vote, that Britain and the EU member states are and will be the closest allies in profound and continuing ways, whether Brexit occurs or not. It is 100% ludicrous to pretend that the UK is a security threat to the EU. And it is 100% absurd that the UK should threaten to develop its own system. The current standoff is infantile and unworthy on both sides. It is high time to grow up and work together for Europe.