It’s easy to imagine Vladimir Putin coming into the shop marked ‘Sweden’, breaking some fine china accidentally on purpose, and growling: ‘Nice little shop you’ve got here. It would be a pity if something happened to it.’ But Sweden is not a pottery shop, Putin is not a Mafia capo, and what’s going on in the Baltic now is not a protection racket.

The Russian president has stampeded both Finland and Sweden, two neutral countries of long standing, into seeking to join the North Atlantic Treaty Organization, the very ‘threat’ that Putin claimed he was trying to drive away from Russia’s borders. The Swedish and Finnish response to his invasion of Ukraine would have surprised Putin. He would see no connection between his invasion of Ukraine, a former Russian imperial possession that needed to be whipped back into line, and two independent countries that have not been in Russia’s sphere of influence for over a century.

They, on the other hand, did see a connection. A neighbour they previously rated as dangerous, but rational, had suddenly revealed itself to be an aggressive and probably irrational gambler.

You might think that Putin’s sheer incompetence would be reassuring to the Swedes and the Finns, but it is not. On the contrary, it frightens them because they are very much in the same position as Ukraine militarily.

They might even be able to stop the Russians dead (and nobody else is in a position to invade them). That’s why the Swedes chose neutrality: they reckoned they were safer that way. If there were a general war, they were not a strategically vital place and they would be very costly to invade, so maybe the major combatants would just leave them alone. The Finns had neutrality thrust upon them by the Soviet Union after the Second World War. They lost a lot of territory to the Russians, but they fought hard enough that Moscow let them be neutral rather than reducing Finland to satellite status.

So why have both countries now decided to join NATO? They are still such tough nuts to crack that they could probably stop the Russians by themselves. And why would the Russians attack only them? Stay neutral, and even in the worst case the Russians will probably pass you by.

That remained a valid assessment until February 24, 2022, and then it suddenly wasn’t. Putin invaded Ukraine, probably to the astonishment of even his own entourage, and from the start began issuing veiled warnings about resorting to nuclear weapons if he was thwarted.

The Russian attack on Ukraine bogged down almost at once, as it was bound to do unless the Ukrainian army was utterly useless. Too few Russian troops, too many lines of attack. And the hints from Moscow about resorting to the use of nuclear weapons to compensate for a conventional defeat multiplied.

This is crazy stuff, and all military skills and hardware that the Baltic countries could bring to bear in a conventional war would be irrelevant if they were faced with similar Russian nuclear threats themselves.

The only effective counter to a nuclear threat is a credible promise of nuclear retaliation. Sweden and Finland have no nuclear weapons, and the only way they can have their security guaranteed by a nuclear deterrent is by joining NATO.

The Swedes still don’t like nuclear weapons, and Prime Minister Magdalena Andersson emphasised that Sweden will not allow foreign troops or nuclear weapons to be based in the country, but the deal is done.

The president of Turkey, Recep Tayyip Erdogan, is demanding that the two Baltic countries expel some anti-Turkish Kurdish activists as a reward for not vetoing this NATO expansion, but this problem will be finessed. It will take months to do the legal work, but in practice the two Baltic countries are already covered by NATO’s nuclear guarantee.