[dragonwriter]

> Chapter 5 only means defending a country that's attacked.

This is true, but there are no limitations on the circumstances of the attack. For instance, if the US was fighting a low-grade global war with an Afghanistan-based terrorist network that has not previously attacked the US anywhere covered by Article 5 because of the geographic constraints of Article 6, and in retaliation for the acts of the US in that war that global terrorist network attacked, say, New York and D.C., then Article 5 would apply, there is no “well, you chose to fight them for other reasons before they attacked you” exclusion.

Now, if Russia only retaliated against French troops in Finland, Article 6 would geographically exclude Article 5 applicability.