The main continental EU countries are out to strengthen their military collaboration. Over the years they have worked away at joint exercises, common weapons procurement, common standards, exchange of personnel, unified commands and shared missions. There are now military interventions undertaken by EU directed troops or naval vessels. The UK has been particularly concerned about being pulled into a European army, owing to the legal constraints that operate on a member state once it has accepted the competence of the EU in any given area. Some think the UK has already consented to more collaboration than is desirable and is now entrapped. Others accept that as we leave the EU we cannot be forced to co-operate or to participate against our will.
The UK has been keener on joint working through NATO, including our US allies. NATO too has a long tradition of common action, shared defence procurement programmes, common standards and procedures, exchanges of personnel and unified commands for given tasks, exercises and missions. It is clear under the NATO charter that whilst we and the other members sign a mutual pledge to defend each other, a NATO member is free to determine their own commitment to any resulting NATO action. NATO is a coalition of the willing, that makes up missions from members in the light of the needs based on consent.
Under President Trump the USA would like the continental countries to make a bigger contribution to NATO defence. The USA points out that European members of NATO rely on US engagement and the common security guarantee for their ultimate protection. Surely, the US asks, the Europeans could at least meet the minimum funding requirement for NATO membership so they are making a bit better contribution to the collective defence?
The UK does meet the minimum requirement, and does possess military capability to join NATO engagements around the world, contributing naval vessels, aircraft and mobile soldiers. UK forces have worked hard to ensure they can co-operate with US forces, as well as undertaking training and exercises with European forces.
Setting our armed services in the context of collaboration and assistance with others does bring a downside. It might mean that we lack particular capabilities where we rely on others, which would limit our own ability to undertake a mission for ourselves. The UK needs to ensure it has sufficient capability to go to the assistance of our own territories or allies, and to defend ourselves at home, whoever the aggressor and whatever our principal allies might think.