EI2 is planned to operate a "light" permanent secretariat based on the network of military liaison officers with the French defence ministry.

[9] The ultimate aim of the EI2 is a shared strategic culture that would enhance the ability of its members to act together on missions as part of NATO, the EU, UN or other ad hoc coalitions.

[1] The participating countries is built around 11 current EU members plus Norway and the United Kingdom;[1] The UK, which has left the EU, was keen to join in order to “maintain cooperation with Europe beyond bilateral ties.”[14] Italy initially was supportive but declined to sign the Letter of Intent with the other 9 members in July 2018; however, it signed the treaty[5] on September 19th, 2019, following a change in the Government coalition.

There are no specific criteria to a state participating in EI2, but it is built around:[15] EI2 seeks some synergies with the Permanent Structured Cooperation (PESCO) that has newly been established within the European Union's (EU) Common Security and Defence Policy (CSDP), and PESCO projects are intended to be integrated into the EI2 where feasible.

[1] France's concern is that developing the EI2 within PESCO would result in lengthy decision times or watered down ambition.