Four months after signing a joint notification on the establishment of a European Union defence pact known as PESCO, ministers from 25 Member States are meeting in Brussels on Tuesday to take their first formal steps towards creating an EU-wide military.

The EU’s High Representative for Foreign Affairs and Security Policy, Federica Mogherini, has already called the gathering a “historical” meeting, as it is the first time that a long bandied-about project to develop a common European defence ...