Op is operating on the understanding that Putin will respect international laws and international boundaries (other than Ukraine's). No way he will step on NATO soil etc
I doubt there are many people on this thread (and I include myself) who know enough about the Ukraine/NATO border to know exactly what is possible or not. The Russian playbook will be to "accidentally" stray into sovereign territory and see what happens. If they really have miscalculated (and they've been 100% right so far) then NATO will pull a trigger and you'll have few dead Russian soldiers for Putin to vow vengeance for.
If, of course, NATO just carries on blustering (i.e as it has done so far) then Putin knows that he can go further. And further.
It's a shame we have no examples from history we could look to for guidance. Well ones that agree with what we're doing, that is.
And when history fails, it's left to poetry to fill the gaps.
IT IS always a temptation to an armed and agile nation
To call upon a neighbour and to say: –
"We invaded you last night – we are quite prepared to fight,
Unless you pay us cash to go away."
And that is called asking for Dane-geld,
And the people who ask it explain
That you've only to pay 'em the Dane-geld
And then you'll get rid of the Dane!
It is always a temptation for a rich and lazy nation,
To puff and look important and to say: –
"Though we know we should defeat you, we have not the time to meet you.
We will therefore pay you cash to go away."
And that is called paying the Dane-geld;
But we've proved it again and again,
That if once you have paid him the Dane-geld
You never get rid of the Dane.
It is wrong to put temptation in the path of any nation,
For fear they should succumb and go astray;
So when you are requested to pay up or be molested,
You will find it better policy to say: --
"We never pay any-one Dane-geld,
No matter how trifling the cost;
For the end of that game is oppression and shame,
And the nation that plays it is lost!"