The EU's diplomatic chief, Ms Federica Mogherini, hailed the agreement as "a new page of European defence", saying countries had already proposed more than 50 projects.
All EU countries except Britain, Ireland, Denmark, Malta and Portugal said Monday they would sign up to the pact, which will be officially launched at a summit next month.
"Today, after so many years, the provision of the Lisbon Treaty establishing the possibility for the European Union member states to have a Permanent Structured Cooperation on defense is going to be initiated", Mogherini told reporters upon her arrival for the council. The EU stresses that PESCO is complimentary to North Atlantic Treaty Organisation, in which 22 of the EU's 28 countries are members.
According to a statement released by Mogherini's foreign affairs council, the pact on the Permanent Structured Cooperation (PESCO) foresees the possibility of a number of European Union member states working more closely together in the area of security and defense.
He explained that tomorrow, during the Foreign Affairs and Defence Council in Brussels, those member states who intend to join PESCO are expected to jointly sign the notification letter addressed to the Council and the High Representative.
In all just five member nations failed to sign up to the process, known as permanent structured cooperation, or PESCO. The move, driven by France and Germany, is misguided.
"I'm a firm believer of stronger European defense, so I welcome PESCO because I believe that it can strengthen European defense, which is good for Europe but also good for NATO", Stoltenberg said.
EU diplomats told RFE/RL on condition of anonymity that Britain's decision previous year to quit the bloc and U.S. President Donald Trump's push for European allies to raise their contributions to the defense of the continent have prompted EU members to act.
Earlier this year, the European Commission launched a major financial incentive for countries to cooperate on defense procurement, with a new European Defense fund worth €5.5 billion per year. The EU, she said, has tools to fight hybrid warfare - the use of conventional weapons mixed with things like propaganda and cyber-attacks - that the American-led military alliance does not have at its disposal.