"Following the migration crisis, many countries realized that the EU would really have to think about their citizens' security," Terras told BNS in Brussels on Thursday. "The migration crisis, events in Ukraine — it all added to it, so that citizens in different countries demanded we think about that in the EU."

According to Terras, the topic of defense was not paid attention to in the EU for years, although the Treaty of Lisbon also provides the opportunity to address the field in the framework of the EU. "By 2013, seven years had passed without the topic of defense being discussed once in the European Council," he noted, adding that PESCO becoming a reality was therefore a surprise, and that Estonia has been involved the process throughout.

On the subject of projects among the 17 areas in the framework of PESCO of particular interest to Estonia, Terras first mentioned the so-called military Schengen, which would make it easier for member states' military units to move to or pass through other member states.

According to Terras, PESCO will not directly organize missions, but the capacities created by it may help when organizing EU military missions. "PESCO should enable the creation of capacities which can be used to support taking part in missions and operations in the EU," he said.

On Nov. 13, 2017, ministers from 23 member states signed a joint notification on the Permanent Structured Cooperation (PESCO) and handed it over to the High Representative and the Council. On Dec. 7, Ireland and Portugal also notified their decision to join PESCO.

The 25 member states participating in PESCO are Austria, Belgium, Bulgaria, Czech Republic, Croatia, Cyprus, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Ireland, Latvia, Lithuania, Luxembourg, the Netherlands, Poland, Portugal, Romania, Slovenia, Slovakia, Spain and Sweden. The U.K., Denmark and Malta did not join PESCO.

The creation of PESCO represents the implementation of articles of the Treaty on the European Union that had yet to be implemented. Member states participating in PESCO retain the sovereign right to command their own national defense, and the capabilities developed within PESCO will belong to member states, who will be able to use them as they wish, regardless of format, including fulfilling their own national needs and those of NATO.

The member states that launched PESCO also adopted a declaration welcoming a political agreement on 17 common projects in areas including training, capability development and operational readiness. These tentative projects are expected to receive the Foreign Affairs Council's official approval in early 2018.