I think it's in NATO's interest to believe in this steadfastly, but my imagination says that there are other scenarios. It's a gamble, but the best way to damage NATO is to make an ambiguous or small attack that makes it not invoke article 5 or to not respond properly.

My imagination says: as soon as new facts are established (let's say blitz invation of a city), you are tempted to not respond because you don't want to start a world war. Of course this fails the overarching theory (MAD, tit for tat etc), but I wouldn't think it's impossible. Maybe for example USA would say it wants to respond with sanctions to avoid a larger war.

This book pretty much lays out those other scenarios:

https://en.m.wikipedia.org/wiki/Foundations_of_Geopolitics

* Use subversive tactics to destabilize countries

* Use natural resource control to pressure countries

* Use military as a last resort when influence fails

Basically, make energy deals with Germany, ignore the US and UK and install puppet governments in Eastern Europe through bribery and propaganda until they can be annexed or granted “special status”.

Ignore US? Well that didn't happen. Former president appears to have some connection and dependence on Russian interests.

* Ignore the threat of US / UK conventional military intervention through threats of mutual assured destruction

> My imagination says: as soon as new facts are established (let's say blitz invation of a city), you are tempted to not respond because you don't want to start a world war.

But how can you establish facts, when you have to kill hundreds or thousands of US soldiers in NATO country first? Do you think that the US will say "shit happens" lets do some financial sanctions? Biden already said that as soon as russians shoot US troops we have WW3. And I think no other conclusion could be drawn here.

The US has troops in the eastern NATO states (Estonia, Latvia, Lithuania ...), more than ever and likely more to come. Biden made it very clear, if russians open fire on US troops (NATO), we have WW3.

Does kind of depend on who is the president of the US.