For many, it was the moment Ed Miliband lost the 2015 General Election. Was he tough enough to stand up to Putin, he was asked by Jeremy Paxman in the pivotal leader’s debate. ‘Hell, yes, I’m tough enough,’ Labour’s youthful leader responded, with all the strength and conviction of a choirboy trying to muster the courage to take his first illicit drag of a cigarette behind the vestry. The audience laughed. And a few days later so did the British people, as they handed David Cameron an upset majority.

Last week Keir Starmer faced his own Putin Test. And failed it just as miserably.

On March 25 the Government announced – to much fanfare – that it would begin to interdict the ‘Shadow Fleet’ funnelling fuel, arms and other supplies in support of Russia’s war in Ukraine. ‘Shadow fleet set to be interdicted in UK waters in latest blow to Russia,’ declared the Downing Street press release. ‘British military will be able to board shadow fleet vessels transiting UK waters as the UK steps up its pressure on Putin.’

So on Wednesday Putin decided to call Starmer’s bluff. The Admiral Grigorovich, a guided missile frigate, and two tankers entered the English Channel at around 9am and proceeded on a leisurely course eastwards past the Isle of Wight and up into the North Sea.

There was no interdiction. No boarding. Instead they were merely ushered on their way by a single vessel of the Royal Fleet Auxiliary. Starmer and Putin had gone eyeball to eyeball. And Sir Keir blinked first.

Over the past month, Starmer’s allies have been roaming the Commons, peddling a new line in their latest attempt to reboot his short-circuiting premiership.

Their narrative asserts that we live in uniquely dangerous times, and with war raging in the Middle East, and the Russian bear stalking the West, Labour MPs should not take the risk of unseating their leader. What I described a few weeks ago as the ‘Get Burnham, Get Nuked’ strategy. But the events of the past seven days have revealed an alternative truth. Which is that we are indeed facing a moment of desperate global peril. And Keir Starmer is temperamentally, and politically, incapable of meeting it.

The Prime Minister’s supporters continue to maintain the fiction he is some sort of master of diplomacy. On Wednesday, as Putin was commandeering the Dover Straits and HMS Dragon was stuck in port in the Mediterranean, they were trying to spin the line he was building a global coalition to open the Strait of Hormuz.

Yet the reality is that over the past week Starmer’s foreign policy has imploded. The start of his premiership was marked by confusion and drift. But one area where he was crystal clear was on his international priorities.

At the top was his desire to forge and cement a relationship with Donald Trump. He would, we were told, become ‘the Trump whisperer’. The siren forces on the Left of his party would be ignored. The simplistic binary option of choosing between Europe and the US would be rejected.

And what has this supposedly deft statecraft delivered? The spectacle of Starmer feebly declaring he’s ‘fed up’ with the US President, while frantically announcing a new pivot back towards the EU. It’s true the Prime Minister cannot be blamed for Trump’s increasingly deranged and megalomaniacal interventions. But it was his decision to place all his eggs in the MAGA basket. And even now he remains in complete denial over the global realpolitik confronting Britain.

On Friday Defence Secretary John Healey was despatched to tell the London Defence Conference that the US remained ‘absolutely locked into’ Nato. Locked in? A week ago Trump was asked if he was considering Nato withdrawal. ‘Oh yes, I would say it’s beyond reconsideration,’ he replied. ‘I was never swayed by Nato. I always knew they were a paper tiger, and Putin knows that too, by the way.’

Starmer’s strength in foreign policy affairs was meant to be that his time as Director of Public Prosecutions – where he had a key role in liaising with the US on counter-terror policy – had placed him at the heart of the security establishment. But as the pillars of 80 years of transatlantic co-operation collapse around him, that is now proving his undoing.

He is too much a prisoner of that establishment to be able to adapt to the new world disorder.

He is also too much a prisoner of his own instincts. As we’ve seen over the course of the Middle East conflict, he has come to equate inaction with statesmanship.

Impotence he recasts in his own mind as commendable patience and caution. Polite diplomatic agreement with his moderate rhetoric is mistaken for influence.

All of which is creating a deeply dangerous vacuum. ‘Defence investment is the Prime Minister’s highest priority,’ the hapless Healey was also forced to parrot on Friday. But it’s simply another fiction.

The Iran war – a war we were not supposed to even have been involved in – has exposed the parlous state of our defences. Yet a year on from Starmer claiming Britain was now on ‘a war footing’, the Defence Investment Plan has not seen the light of day, nor even has a date for publication. And here is the other brutal truth. Even if Starmer genuinely wanted to begin to rearm the nation, he wouldn’t be able to. He is a Labour leader at a time of austerity. He has neither the authority, nor political capital, to place the defence of the realm at the top of his agenda.

His party won’t allow it. The idea Starmer can convince his MPs to vote through cuts to the NHS, welfare, education and investment in Britain’s hollowed-out public services to pay for tanks and bombs and drones is a pipe dream.

Which leads us to the final truth. No leader can enjoy respect abroad unless they have first earned respect at home. And few prime ministers of the modern era have plunged to such pitifully low esteem, so rapidly, as Sir Keir.

Labour ministers are putting the finishing touches to their leadership campaigns. Labour MPs are preparing their next parliamentary ambush. The voters are planning to deliver their own contemptuous verdict in next month’s local elections. And Putin, and Trump, and Britain’s other adversaries know it. In Moscow they can smell Starmer’s weakness. And they are already planning how next to exploit it.

That is the true danger facing Britain. We now have no foreign policy. We have no defence policy. We have no major strategic alliances. Keep Starmer. Get nuked.