It was a misjudgment by Sweden and Finland that they believed Erdogan was only blocking their entry into NATO to get hold of American fighter jets.
The F-16s he wants are important to him, no question.
But the Turkish President was also concerned with substantial concessions from the two Nordic countries.
The Kurdish question is always more important to him than the strategic situation in north-eastern Europe.
The governments in Stockholm and Helsinki have now delivered what Erdogan is asking for.
They even had to promise not to support the Syrian Kurdish militia YPG.
This is a broad definition.
The militia is one of the West's most important allies against "Islamic State".
She made a major contribution to crushing the terror caliphate a few years ago.
The United States still relies on them today.
That's not the only bitter pill in the memorandum that the two candidates signed in Madrid on Wednesday night.
A stricter fight against terrorism, the extradition of Kurdish extremists and arms deliveries to Turkey are also part of this.
Each of these points may be understandable on its own.
All in all, however, they mean a farewell to Sweden, in particular, from its decades-long role as a moral superpower.
The two countries already have to learn in the accession process that giving up neutrality brings with it political constraints that could be avoided when one was still on the sidelines.
They share this experience a little with Germany.
The fact that Finland and Sweden are willing to pay this price is due to Putin, who, in his overconfidence, felt he had to threaten these two countries himself.
Joining NATO adds another strategic dimension to his list of unintended consequences of war.
It will soon have an external border with the western alliance that is 1,300 kilometers longer.
Only in his distant imagination, however, is this a threat to Russia.
NATO is and will remain a defensive alliance.
For this purpose, the accession of the two countries is a strategic asset for the alliance.
It will stretch its protective umbrella over one of the last remaining gray areas in Europe's security order.
Any westward attacks are increasingly risky for Putin, thanks in large part to the military prowess of the United States, which remains the backbone of NATO to this day.
It is bad that another way of living together in Europe is currently not possible.
But what applies to Sweden and Finland also applies to the states that are already members of the alliance: one can no longer hope for good intentions in Moscow, now it is a question of deterrence.Keywords: