The war happened because NATO kept expanding eastwards. Stoltenberg has now publicly acknowledged that Putin made clear to NATO in a draft treaty before the war that it could avert it if NATO agreed not to keep enlarging. But NATO rejected the offer.

Then lastly on Sweden. 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.

The opposite happened. He wanted us to sign that promise, never to enlarge NATO. He wanted us to remove our military infrastructure in all Allies that have joined NATO since 1997, meaning half of NATO, all the Central and Eastern Europe, we should remove NATO from that part of our Alliance, introducing some kind of B, or second class membership. We rejected that.

https://www.nato.int/cps/en/natohq/opinions_218172.htm#:~:text=The%20background%20was%20that%20President,condition%20for%20not%20invade%20Ukraine