Talk of joint efforts to defend Europe is on the lips of EU leaders after decades of leaving collective security mostly to the United States and NATO.

Nobody is suggesting a joint European army, with thousands of tanks and combat planes displaying the EU's star-studded logo.

But at a summit in the Slovak capital on Friday, heads of 27 countries named common defense as one of the goals needed to bring the bloc forward.

Declared French President Francois Hollande, "There is no continent, there is no union, if there is no defense."

The EU's Lisbon Treaty, which took effect in 2009, foresaw a mechanism for permanent defense cooperation inside the bloc.

But squabbles among member states have kept the topic in the background at most previous meetings of European leaders.