Brexit: implications for national security

According to the Treaty on European Union, national security remains the sole responsibility of member states.

Consequently, the sharing of secret intelligence is generally conducted on an intergovernmental level, outside of the EU framework, and beyond the jurisdiction of the Court of Justice of the EU. The UK will remain at liberty to maintain such relationships and agreements, or to enter into new ones, regardless of the outcome of the Brexit negotiations. It has thus been argued that the impact of Brexit in this area will be minimal. 

However, representatives from law enforcement and the intelligence and security communities have emphasised the importance of EU wide cooperation in tackling security threats, through the sharing of information and data, participation in agencies, and a coordinated strategy.