Threats to Britain from Russia’s invasion of Ukraine are “alive and well” and “no longer a distant possibility”, the head of the UK’s defence review has said.

Former NATO chief Lord Robertson is leading a “root and branch” review of the UK’s armed forces, launched by Prime Minister Sir Keir Starmer, to assess the defence challenges the country faces.

Speaking in the House of Lords today, he pointed to the “depraved conduct” of Russian forces as an example of what was at stake and said it was vital that the UK’s military was strong enough to deter any threat.

“We need to recognise… that the threats to our country and our citizens are no longer theoretical. They are no longer a distant possibility,” Lord Robertson said.

“They are alive and well in Ukraine today, where Vladimir Putin’s Russia has brutally invaded and sought to occupy a peaceful, neighbouring independent nation-state.

“Anybody who needs reminding of what the stakes are in the world today need only look at the depraved conduct of Putin’s occupiers in those parts of the Donbas and Crimea that they presently and temporarily occupy.”

During a debate on the subject, Lord Stirrup said the UK should not put off increasing defence spending, saying that Mr Putin would “not wait upon our pleasure”.

“I suppose we could send him a note saying: ‘Dear Vladimir, we know that you’re a dire threat to the peace and security of Europe, but would you mind holding off until we get the books straight?’ I doubt that he would pay attention,” he said.