Article 5 was implemented only once—when the US was attacked on 9/11. It is the reason why NATO was/is involved in Afghanistan.
I understand completely.
The current circumstances aren’t the same. Events are still manageable if they had the will.
What is war but failed diplomacy?
Economic pressure is the proper method. Tell Russia that they would be financially responsible for any area they would annex. The IMF loaned Ukraine $18B and since Crimea is still recognized as sovereign territory, Russia would have to pay proportionally.