While the UK and France are wary it could undermine NATO, Germany has backed the idea.

"An army like this would help us to better coordinate our foreign and defense policies, and to collectively take on Europe's responsibilities in the world," the European Commission President Jean-Claude Juncker said in an interview to Germany's Welt am Sonntag newspaper.

He added the EU's image "has suffered dramatically and also in terms of foreign policy, we don't seem to be taken entirely seriously."

"A joint EU army would show the world that there would never again be a war between EU countries,"Juncker said.

With a joint EU army, the bloc could "react more credibly to the threat to peace in a member state or in a neighboring state."