Why? Let them invade another country, let them hack our infrastructure next such as our water supply? You think letting it go or doing nothing is the answer? This guy Putin is no different than Hitler, let him do this sort of thing and you will have much bigger problems in a couple of years.
Boy am I glad you're not in charge of foreign relations, for the sake of nearly every country in the world. "War? Whatever, so be it!". Right? A complaint often surfaces from those that have actually lived through wars: How disconnected people are from war. Your country (I'm assuming) has been at war with various bits of the middle east for over a decade and you are not suffering the consequences. It's all remote for…
The point is not to let these guys do whatever they want. Go into Ukraine, kill UN volunteers in Syria. Let them become emboldened by different types of attacks and tomorrow we will have the type of war your talking about.
Handle these problems now that they are small.
Edit: I wanted to add that it is very often the ones who have seen what terrible tragedies happen when you let terrible people like Putin do what they want that are the biggest "warmongers". It is why you see the Israelis become so eager to defend themselves because they have seen what will happen if you don't take care of bad people like Putin when they are small.