The formal accession today of Finland to Nato marks a significant expansion of the Western alliance and represents a major strategic setback for Vladimir Putin, compounding Russia’s military debacle in Ukraine. The symbolism is hard to exaggerate. Putin claimed that part of his rationale for the invasion was to stop the encroachment of Nato. But Ukraine is not part of Nato. Indeed, had it been, Putin would not have dared attack it for fear of triggering the mutual defence pact.

But his aggression has prompted two previously neutral countries – the other being Sweden – to seek to join. Following its recent general election, Finland will today become the 31st member, adding 800 miles of Nato bordering on Russia, the antithesis of what Putin supposedly intended.

While the singular failure of the Russian military to defeat Ukraine is a daily reminder of the folly of the Kremlin’s belligerence, the Nato expansion is arguably an even greater blow to the credibility of Russia’s leadership. How does Putin explain to his people that the deaths of thousands of young men were in any way justified now the war has had the opposite effect to that intended?

Russia threatened “a military technical response” when Finland indicated a desire to join Nato last year, and as a full member it can now rely on Article 5 protection. The country brings to the alliance a well-trained, highly equipped army numbering up to 280,000 soldiers once fully mobilised, with conscription still retained.

Since the invasion of Ukraine, Putin has managed to expand, unify and strengthen Nato, which from the Kremlin’s standpoint is a geopolitical blunder of historic proportions.