Remarks by Donald Trump normally reverberate in an echo chamber of his own creation, a sort of vacuum that often strips them of any consequence globally. It is white noise, one might think – rhetoric designed to project strength and the rejection of the status-quo, rather than an expression of any actual policy. It is just Trump being Trump.

But when the former president suggested on Saturday that he would let Russia do “whatever the hell they want” to any NATO member that doesn’t meet spending guidelines, the impact was acute.

He recalled what he said was a conversation with a “large” NATO ally – it was unclear who he was referring to or when the conversation took place – which, according to his telling, had declined to spend the 2% recommended equivalent of their GDP on defense, but nevertheless wanted assurances from the US that they would be protected if Russia attacked. Trump said he would not give such an assurance, as the ally was “delinquent,” and Russian President Vladimir Putin should feel free to have his way.

Trump’s opinion of NATO has been known for years – he thinks it is the epitome of everything he despises about of America’s allies, taking advantage of US strength without giving anything in return: a store loyalty club in which you get points without proportionate spending.

As with much foreign policy, the Republican frontrunner radically misunderstood the nature and purpose of this relationship. NATO is not an alliance based on dues: it is the largest military bloc in history, formed to face down the Soviet threat, based on the collective defense that an attack on one is an attack on all – a principle enshrined in Article 5 of NATO’s founding treaty.

It’s purpose which suits the US profoundly: The White House invoked Article 5 after 9/11. And since NATO’s creation, US might has been often packaged globally as the expression of a dozens-strong consensus. NATO helps bolster the US’s ebbing position as the sole hyperpower. Strip away this vast alliance, and its diplomatic and economic might, and the US looks quite lonely on the world stage.

In short, the US will almost certainly always spend much more than anyone else on its military, regardless of its allies. NATO gives it a global bedrock of legitimacy, support for the dollar, and the post-Soviet hegemony it thrives upon.

Saturday’s misunderstanding considered, Trump’s comments come at a devastatingly bad time for Europe. The rogue rump of the GOP which supports him is persistently trying to derail vital aid to Ukraine. If the desired $60 billion does not arrive, or is delayed much longer, it will have an irrevocably detrimental impact on Ukraine’s practical defenses at the frontlines, political cohesion in Kyiv, and nationwide morale.

Damage is already being done. And it is Putin who benefits.

It is still a mystery as to why Trump feels so inexplicably bound to Putin, and wedded to his flattery, or even success. It is a riddle we may only understand in the fullness of time. Is it a warped attraction to a “bad guy,” a crush on Russia’s deeply patriarchal culture, or something more darkly tied to Trump’s personal history itself?

Saturday’s incendiary comments feed a narrative of the US being exploited, under-appreciated, and in global decline as a result. Trump’s GOP feeds on this, perhaps unaware it is a self-fulfilling loop of grievance. The more the US bemoans its allies and their miserly neglect of NATO, and withdraw from it, the less powerful it is.

The insufferably softball Putin interview by former Fox News host Tucker Carlson fomented the projection of weakness: it was an easy, open ear for the Kremlin head’s frail arguments of persecution and laughable historical justification for invading a weaker, non-threatening neighbor. The platform signalled parts of America want to listen to Putin’s nonsense, and enabled them to do so. It heralded the likely stark change in relations with Russia of a Trump second term.

While the real-world impact of Trump’s comments are not yet clear, they could be catastrophic. European security hinges on Ukraine’s success, or at the very least its ability to hold back and weaken Russia’s continuing assaults.

If Moscow prevails, it could take years; in the meantime, Putin has now managed to re-focus his economy and society for wartime, and might find it anathema to his grip on power to stop the drums of conflict beating. Russian advances in Zaporizhzhia could lead to movement into Kherson, then Mykolaiv, and Odesa, putting Putin on the doorstep of NATO’s Romania.

But do not expect Moscow to launch a full-on invasion of the largest military alliance in history. Russia will not suddenly bomb France. Putin prefers to needle, to provoke, and test his opponents’ redlines or readiness. Is NATO willing to go to war with Moscow over Russian-speaking parts of the Baltic state of Estonia? Or the tiny, partially Russian-inhabited Norwegian island of Svalbard? Would a minor Russian provocation slowly expose NATO disunity and their reluctance to mobilize their populations for conflict in the same way Russia has?

Europe has for nearly a decade lived with the possibility it might face the Russian threat alone. Trump’s first term sounded a loud klaxon to that effect. But now there is the largest land war to hit Europe since the 1940s, making the danger more acute.

The UK has recently switched its broader rhetoric in recent weeks to suggest the West is no longer in a post-war but a pre-war world. Senior military Britons have even mulled whether conscription is even a possibility. Finland and Sweden have urgently sought to join NATO. Germany’s foreign ministry responded to Trump’s comments with “One for all and All for One”. The European Council President Charles Michel slammed Trump’s “reckless statements”.

But European defense has rarely thrived without the might of US support. Moscow is, after its failed invasion of an unprepared neighbor, still weak comparatively. It is not a behemoth capable of raging across Western Europe. It is far from the potent military it was perceived to be in 2021. Yet make no mistake: the lack of a guarantee of American support massively undermines NATO’s effectiveness. It calls into question the alliance’s cohesion and therefore its existence.

Trump knows that. He is not simply saying the US won’t help NATO allies who haven’t paid. He is saying he would encourage Russia to attack, invade, inflict the horrors of Mariupol upon US allies. It may be noise, it may be aimed at whipping up the faithful in front of his podium. But it was heard loudly, especially in European capitals and Moscow.

Part of Trump’s appeal to his supporters is his lack of presidential poise. But after Ukraine’s invasion two years ago, this is no longer a game of posturing. It is a moment that hopefully the history books will not have to look back and analyze as having been of grave consequence.