Germany’s defence minister said on Monday the European Union must modernise its military defence and security to match NATO’s drive to beef up its own security forces in the wake of a major Russian build-up.

France, Germany, Italy and Spain are calling for a common European defence policy after Britain’s vote to quit the bloc, an initiative that marks the EU’s biggest push since the 1990s.

“We have seen an enormous modernisation drive by NATO over the past three years because of the Kremlin’s behaviour,” Ursula von der Leyen told a security conference hosted by the conservative Christian Democrats.

“That was correct and important, but I believe that we must invest at the least same energy into a modernisation of the European security and defence union,” she said.