The Finnish President and the Swedish Prime Minister were not yet allowed to walk over NATO's blue carpet on Wednesday morning.
To a certain extent at the last minute, they had allayed Turkey's concerns about joining the alliance the night before - with a kowtow to President Recep Tayyip Erdogan.
But to get the status of an "invitee" was no longer enough.
Only states whose accession protocols have been signed by all members have it.
They are allowed to take part in all meetings of the alliance, but they can only vote once the protocols have been ratified in all states.
The Finn Sauli Niinistö and the Swede Magdalena Andersson were able to cope well.
In the second session in the afternoon they were allowed to participate as partners,
Thomas Gutschker
Political correspondent for the European Union, NATO and the Benelux countries based in Brussels.
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The relief at the agreement reached the night before was palpable on Wednesday.
"We can see that the allies are able to demonstrate unity," said Jens Stoltenberg when he was the first to stand on the blue carpet at eight in the morning.
"I believe that we will hardly find another accession process where there are only a few weeks between the application, in mid-May, and the invitation, which will be made today."
A "historic decision"
The fact that it was only a few weeks and not months was due to Stoltenberg himself, who mediated carefully, as in previous crises between Greece and Turkey.
The invitation of the allies to join followed on the heels of the heads of state and government gathered in Madrid on Wednesday.
The accession protocols are to be signed immediately after the summit.
Joe Biden also acknowledged the breakthrough when he was greeted by Stoltenberg at the exhibition center in the Spanish capital in the morning.
The American President spoke of a “historic decision” that would make the alliance stronger.
Biden had been very committed to the admission of Finland and Sweden and had given both countries a security guarantee for the meantime until ratification was complete, which is equivalent to the alliance obligation under Article 5.
He also coined one of the quotes that stuck with him from that day: “Putin wanted the Finlandization of Europe.
He will get the Natoization of Europe.” The catchphrase Finlandization was used to describe the special relationship between Helsinki and Moscow during the Cold War.
Finland remained non-aligned and, as a small neighbor, tried to maintain good relations with the militarily far superior Soviet Union.
The country is finally shaking off this form of dependency.