[1] PESCO is similar to enhanced co-operation in other policy areas, in the sense that integration does not require participation of all EU member states.

It added the possibility for those members whose military capabilities fulfil higher criteria and which have made more binding commitments to one another in this area with a view to the most demanding missions shall establish permanent structured cooperation (PESCO) within the EU framework.

PESCO was seen as the way to enable the common defence foreseen in Article 42, but the scepticism towards further integration that had arisen around the rejection of the European Constitution meant its activation was unlikely.

Further, for Germany, it was about building capabilities and giving a post-Brexit signal of unity, whereas France was focused on operations and looking for help for its overstretched African deployments.

PESCO would be inclusive, but not all states had to take part in all projects and progress would be phased allowing the development of new, common capabilities without having to resolve larger differences on end-goals first.

[6][7] On 7 September 2017, an agreement was made between EU foreign affairs ministers to move forward with PESCO with 10 initial projects.

[12][13] Denmark did not participate as (prior to its abolition in July 2022) it had an opt-out from the Common Security and Defence Policy, nor did the United Kingdom, which withdrew from the EU in 2020.

Those Member States whose military capabilities fulfil higher criteria and which have made more binding commitments to one another in this area with a view to the most demanding missions shall establish permanent structured cooperation within the Union framework.

[30] In May 2021, Turkey applied to participate in the Military Mobility project, but this was opposed by Austria in addition to the existing tensions with Greece and Cyprus.

[33][34] On 6 October 2022, at the 1st European Political Community Summit, British Prime Minister Liz Truss committed the United Kingdom to joining PESCO and its Military Mobility project.

The measure was passed, with the government arguing that its opt-in nature allowed Ireland to "join elements of PESCO that were beneficial such as counter-terrorism, cyber security and peace keeping ... what we are not going to be doing is buying aircraft carriers and fighter jets.

[18] In Switzerland, an opinion poll conducted two months after the 2022 Russian invasion of Ukraine showed support for the country joining PESCO.

Major armament projects are intended in the future (EU forces use 178 different weapon systems compared to 30 in the US), but initially PESCO is to be focused on smaller operations to lay groundwork.

Potential future PESCO projects include the following existing intergovernmental cooperations between member states' militaries, presently outside the CSDP framework:[citation needed] Forces and command centres: Bodies fostering integration: Other initiatives of the Common Security and Defence Policy established after the introduction of the European Union Global Strategy: Other 'European' defence organisations that are currently not part of the CSDP but could potentially become PESCO projects: