Remarkable – and relatively speaking a blessing – that the wake-up call for Britain to take defence seriously again did not come in the form of a military attack on UK soil, but instead was triggered by the verbal assault of Ukraine’s wartime leader by a sitting US president.

The lack of any physical destruction on British streets, though, should fool no one in government or wider society that the framework of security that has protected the country and its allies since the end of the Second World War is not at best cracked and at worst shattered.

Instead, check out one of the latest posts by Elon Musk, Donald Trump’s “disrupter-in-chief”.

He used his social media site X to say “I agree” with a call for the United States to leave NATO – a transatlantic alliance, and the bedrock of European security, that the new administration had until now continued to back at least in public.

It is yet another example of escalating hostility from the new Trump White House – which has sided with Russia against Ukraine, lashed out at its European partners over their values, and even suggested absorbing Canada as the 51st American state.

The alarming mood-change by a nation that is meant to be a friend surely demands an equally dramatic shift in approach by NATO’s 30 European allies and their Canadian partner.

Rather than stating the obvious – that American support can no longer be taken for granted – they should instead be actively adapting to a world in which it fundamentally no longer exists.

Make no mistake, this would be a daunting and humbling prospect – perhaps too awful even to contemplate, in particular for the UK, which has tied itself militarily so closely to the US for pretty much everything from intelligence sharing and technology to nuclear weapons.

Britain is not alone. All European militaries, as well as Canada, to a greater or lesser extent rely heavily on their more powerful American partners.

Breaking that dependency would require a rapid expansion in military capabilities and capacity across the continent, as well as a huge effort to build up the defence industrial base required to produce weapons at scale and exploit emerging technologies.

Sir Keir Starmer – who is hosting a Ukraine summit of allies on Sunday – has rightly adopted the UK’s natural position of leadership in Europe in the wake of Donald Trump’s extraordinary hostility towards Volodymyr Zelenskyy. He gave the embattled Ukrainian president a warm embrace on Saturday when the two met at Downing Street.

Britain is one of Europe’s two nuclear-armed states, a powerful voice within NATO, and a permanent member of the United Nations Security Council.

But talking tough on defence and the need to support Ukraine as the US steps back is no longer enough in a world where hard power is the only real currency once again.

A pledge by the prime minister to increase defence spending to 2.5% of national income by 2027 and to 3% in the next parliament is of course a step in the right direction.

Yet unless it is accompanied by much greater speed and urgency coupled with a genuinely generational shift in the entire country’s approach to national security then it will go down in history as the headline-grabbing but otherwise empty gesture of a government that has forgotten what it means to be ready to fight wars.

Anneliese Dodds, who quit as international development secretary on Thursday over the prime minister’s plan to fund his increase in defence spending with a raid on the overseas aid budget, summed up the challenge well in her resignation letter.

She wrote that she supported the plan to lift the defence budget but said even 3% “may only be the start, and it will be impossible to raise the substantial resources needed just through tactical cuts to public spending”.

She added: “These are unprecedented times, when strategic decisions for the sake of our country’s security cannot be ducked.”

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Ms Dodds is right.

It is no longer good enough to treat defence, deterrence and wider national resilience as a niche subject that is delivered by an increasingly small, professional military.

Rather, it should once again be at the heart of the thinking of all government departments – from the Treasury and business to health and education – led by the prime minister, his national security adviser and the cabinet secretary.

This is not something new. It was normal during the Cold War years when, after two world wars, the whole country was acutely aware of the need to maintain costly but credible armed forces and a population that was ready to play its part in a crisis.

Sir Keir Starmer has suggested a coalition of European allies could step up and defend a potential deal for Ukraine to “guarantee the peace”.

The prime minister indicated some EU nations could be prepared to increase defence spending to protect any peace deal that is agreed between Ukraine and Russia.

But speaking at summit of EU leaders in central London, Sir Keir acknowledged that no such coalition had yet been formed and that “not every nation will feel able to contribute”.

Instead, he said “those willing” – though he did not state which countries this included – would “intensify planning now with real urgency”.

In a sign this could mean troops from member states being sent to Ukraine, he added: “The UK is prepared to back this with boots on the ground and planes in the air, together with others. Europe must do the heavy lifting.”

The UK can still trust the US with Ukraine’s future despite the bad-tempered clash at the White House between Donald Trump and Volodymyr Zelenskyy, a minister has said.

Cabinet Office minister Nick Thomas-Symonds told Sky’s Sunday Morning with Trevor Phillips there was “no ambiguity” over whether the US continued to be an important ally for Britain despite the unpleasant scenes that unfolded in the Oval Office on Friday.

There are concerns among Western leaders that the exchange – which resulted in Mr Zelenskyy leaving empty-handed and without having signed an important minerals deal to continue US support – could result in the White House withdrawing aid for Ukraine’s war effort.

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But Mr Thomas-Symonds, who is also minister for the constitution and European Union relations, said he believed we could “still trust the Americans”.

And he said that in the event the US did pull financial support for Ukraine, the UK would “continue to be an honest broker” and “bring the different parties together”.

Echoing the US’s president’s language, he added: “We will also continue to make the case that peace is made from a position of strength, not a position of weakness.

“So, it remains critical to put Ukraine in the strongest possible position.”

On whether Britain could still trust the Americans, Mr Thomas-Symonds replied: “Yes, I do believe we can trust the Americans.

“We do have an ally in the United States that we can trust,” he continued. “There’s no ambiguity about that.”

Sir Keir Starmer’s desire to act as bridge between the US and Europe will be tested as he hosts a number of EU leaders for a summit in London.

Present will be the leaders of Italy, France, Germany, the Netherlands, Poland, Spain, Finland, Denmark, Norway, the Czech Republic and Romania. Canada and Turkey will also attend.

The PM’s role as a peacemaker takes on greater significance following the breakdown in relations between Mr Trump and Mr Zelenskyy that unfolded in front of the world’s TV cameras.

In the aftermath of the fallout, Sir Keir phoned Mr Zelenskyy and invited him to Downing Street on Saturday ahead of today’s summit in a show of support for Ukraine.

He also phoned the US president, saying his “driving purpose” was to “bridge this and get us back to the central focus”.

Turning to the scenes at the Oval Office on Friday, Mr Thomas-Symonds admitted he had “never seen anything quite like that”.

“Obviously that is not how it should have happened.”

His sentiments were echoed by shadow foreign secretary Priti Patel, who said she was “absolutely aghast” at “the whole spectacle” which saw Mr Trump accuse the Ukrainian president of “disrespecting” the United States and “gambling with World War Three”.

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In a sign of how badly the meeting went, the minerals deal the pair had expected to sign – which would have established a new fund for the US to invest in Ukraine’s minerals, rare earth materials and other valuable natural resources – was put on ice.

Mr Trump viewed the minerals transaction as a fair way to recover the billions of dollars that the US has given Kyiv in its war effort and as necessary to guarantee further US military support for Ukraine.

Ms Patel said the scenes at the White House were “unedifying and undignified”.

“When we look at President Zelenskyy…I think he’s a hero,” she went on.

“He’s an absolute hero in the way in which he stood up to authoritarianism. He’s fighting for the sovereignty of his country.

“He also know when the going gets tough. You keep your disagreements not in front of cameras, but you keep them private. So, you know, we are where we are.”