Der Link ist im Artikel, genau hinter dem Zitat, ist gar nicht so schwer zu finden.
https://www.nato.int/cps/en/natohq/opinions_218172.htm
"First of all, it is historic that now Finland is member of the Alliance. And we have to remember the background. The background was that President Putin declared in the autumn of 2021, and actually sent a draft treaty that they wanted NATO to sign, to promise no more NATO enlargement. That was what he sent us. And was a pre-condition for not invade Ukraine. Of course we didn't sign that."
Was genau in dem Entwurf stand, wirst du wohl Stoltenberg fragen müssen.