- 23 EU member states signed a military cooperation agreement this week.
- Permanent Structured Cooperation (Pesco) provides deeper integration.
- The UK, which has historically opposed such steps, is one of five hold-out nations.
A large majority of EU nations have signed up to a defence co-operation pact which moves the bloc closer to having its own military capability.
Twenty-three of the European Union’s 28 nations agreed to the initiative, officially known as Permanent Structured Cooperation (Pesco), at a meeting of defence ministers in Brussels on Monday.
The hold-out countries were Malta, Denmark, Ireland, Portugal, and also the United Kingdom, which is leaving the bloc in 2019 and has long opposed EU defence cooperation.
Formally, EU member states are responsible for their own defence arrangements, despite the extensive integration which has taken place in other areas.
But a series of initiatives over the years have sought to increase the bloc's ability to act as one in defence matters. The process is complicated because EU nations have militaries of vastly different sizes, capabilities and traditions.
Most - but not all - EU nations are members of NATO. Some have been very active militarily in the past, while others are more reluctant. Some, like Germany, require parliamentary votes to engage in operations, while others do not.
Pesco is the latest attempt to bridge these divides and let European militaries work together.
The text of the agreement, presented to the European Council yesterday, outlined 20 commitments which all states agreed to.
It includes an aim to prepare for "a potential deployment of an EU BG" (battle group), as well as agreements on increasing cyber security, and relaxing restrictions on moving military equipment and personnel across EU borders.
According to The Times newspaper, early examples of Pesco projects could include a medical evacuation and field hospital unit.
The newspaper reported that Boris Johnson, the UK foreign secretary, said that Britain is "supportive" of the initiative despite not joining it.
He described the UK Armed Forces as "like a flying buttress to support the cathedral" of European defence - i.e. an external but important part of the arrangement.
During the campaign before Britain's EU referendum, the official leave campaign warned that increased cooperation would ultimately lead to a fully integrated European army.
The UK government had long been a drag on military co-operation efforts, but the idea has gathered new steam since Britain's vote to leave.
Although the 23 nations agreed on their commitments this week, the arrangement still needs to be formally adopted by the European Council, which said it hopes to do on December 11.