NATO Secretary-General Jens Stoltenberg confirmed that he supported the plans of the EU to build a common defence policy, but he warned against any rapid reaction force that might duplicate allied operations. EU defence ministers are considering creating a "first entry force" of 5,000 troops, saying the bloc needed to react to conflicts beyond its borders, spurred by the chaotic Western withdrawal from Afghanistan.

"We welcome more EU efforts on defence, but that cannot replace NATO. It should not duplicate NATO, because we have one set of forces, we have scarce resources," Stoltenberg said, quoted by Reuters.

The EU's efforts to create a force have been paralysed for more than a decade, despite the creation in 2007 of a system of EU battalion-sized battlegroups of 1,500 troops that have never been used due to disputes over funding and reluctance to deploy. "I mean you have to use them in the best possible way. The EU has had battlegroups for many years, they have not been deployed," he said. NATO created a Very High Readiness Joint Task Force (VJTF) in the wake of Russia's annexation of Crimea from Ukraine in 2014, with the United States contributing high-end military assets. The EU, most of whose members are in NATO, says it must be able to act independent of its U.S. ally in the Western alliance, the world's foremost military power, in Europe's backyard to defend its own interests.