Isn’t that how WWI started, with allies rushing to defend allies over some backwater?
Bismarck grunted assent and said it "would begin with some foolishness in the Balkans." He also said there was nothing there worth the life of a single German soldier.
Some 16 years later, he would prove prophetic.
That's not why it started, but there is always a catalyst to act as a reaction initiator.
To those who's beliefs are along the lines of "leave them be" for fear of starting a war, I would ask them to furnish a working plan for the alternative.
Trouble is, that there really is not one that would work because by that time they are unworkable. by that time appeasements and talk have all led to the inevitable.
That's the history of it. So the reality is that the global community has to act in the initial phase of the conflict that always grows.
In Obama's most recent blunder, he allowed via appeasement, and talk, the Russian camel's nose under the tent.
As you can plainly see, the rest of the camel soon follows suit.