The General added: "Europe faces a growing external threat in an evolving world order at the same time as its political, fiscal and industrial systems are struggling to respond. After decades of underinvestment in defence, this is no longer merely inefficient – it is dangerous." His intervention comes in a new paper from a think tank founded by former Prime Minister Tony Blair, which was developed alongside similar groups from the continent.

It argues Europe "should be a superpower: economically, politically and militarily," but that the continent's failure to act reflects "decades of strategic complacency."

The chilling warning states European security has rested on "fragile assumptions" since the end of the Cold War, including that the US would remain a "global policeman" and that China could be managed through "rules and institutions".

It argues that these assumptions "did not collapse overnight - but the world around Europe has hardened".

The report, backed by General Sir Nick, sets out five tests it says European leaders must meet to ensure the region's future safety.

They include backing Ukraine in its ability to defend itself from future aggression, imposing further limitations on Putin's abilities to interfere in electrons and addressing a slump in defence spending.

Whilst the paper backs the continent remaining within NATO, it cautions that European states must contribute more rather than relying on the United States.

An MoD spokesperson said: "Our commitment to NATO is unwavering and we are stepping up on European security, with a NATO first approach and UK leadership of the Coalition of the Willing to secure a peace in Ukraine."

They added: "As the Strategic Defence Review set out, lessons learnt from Ukraine driving a landmark shift in the UK's deterrence and defence capabilities, backed by the largest sustained increase in defence spending since the end of the Cold War including an extra £5billion for defence this year alone."

However the government's current approach to defence has been panned by critics, including the Conservative Party. The government's handling of the Chagos deal, which would see the UK handing billions to a foreign government, has been slammed by James Cartlidge, the Shadow Defence Secretary before.

He previously called for the government to ditch the plan and "spend the money on our armed forces instead".