Barack Obama has accused Europe of being “complacent” about defence by failing to meet the Nato two per cent spending target.

It came as he delivered a passionate plea for the European Union to hold together, saying it is one of the “greatest political and economic achievements of modern times”.

In an address in Hanover, the US President said that Nato must spend more to address the crises in Syria and north Africa and to invest in new missile defence and cyber systems.

Nato is also increasing troop numbers and equipment in its eastern European neighbours who feel at risk of Russian destabilisation.

Mr Obama warned that states are failing to pay their “full share” of spending two per cent of GDP on the military. “I’ll be honest, sometimes Europe has been complacent about its own defence,” he said.