Triggers are how bullets are launched.
They have some kind of restraining mechanism that needs to be overcome: the most traditional being the application of the pressure of an index finger to the physical trigger.
That pressure moves the spring restrained trigger forward until the restraint of the spring is over-ruled and the sharp central piece of the hammer of the trigger - the firing pin - flies forward, unrestrained.
The pin hits a small casque of extremely volatile material that is mounted in a metal container in the center of what is called a bullet.
A bullet is a metal projectile designed to fly through space, and if properly pointed - aimed - hit something.
The tiny explosion of the casque ignites a much larger store of explosive power and the bullet flies out of the thing in which it has been mounted - its casing, or shell - and the bullet goes somewhere as accurately as it has been aimed.
Putin's move into Ukraine may be a trigger situation.
Based on world history since Louis XIV of France it probably is.
A trigger situation.
The trigger in 1914 was the assassination of Archduke Ferdinand of Austria.
Within days the world was in a war that was gridlocked by treaties and alliances that, if honored, would produce exactly what it produced, because they were slavishly honored: mass death and loss of empire.
The loss of empire was probably a good thing but, at the cost of millions and millions of young men, one needs to question whether anything was accomplished.
Putin MUST take Ukraine; no cost will be too much; if he fails he is FINISHED.
But if he is able to take Ukraine he needs to move on.
Ukraine is in his opinion a piece of Russian territory that has been taken over by drug addicts and Nazis.
He hasn't explained how that all happened, but when one is a dictator assertion is fact.
So the trigger is Ukraine.
The casque is Poland and the Baltic democracies.
Which is where Vlad MUST MOVE NEXT.
For Ukraine to make any sense he must re-establish the buffer states.
Buffer states is such a 19th century concept that I am consistently amazed at its Twenty First Century durability, but it is still there.
Especially in Russia.
Which never left the Sixteenth Century.
Also, he has a troublesome little piece of Russia - Kaliningrad - on the Baltic Sea, surrounded by EU States, that he needs to get neatly consolidated into his Vlad the Puter Empire.
Anyway, back to the analogy: the larger store of explosive material in the analogous bullet is Article Five of the Nato Charter.
That explosive material in this analogy - they all limp - is more, though, that just Article Five.
The rest of it is what Putin does after a half million Nato forces enter Poland and the Baltics to sweep the Russians out of The European Union and NATO.
Once that happens Putin has a decision.
If he decides on nuclear war, which he has already said was for sure, WE/NATO/EUROPEAN UNION will retaliate - the difference between attack and retaliation, after all, only being milliseconds, but milliseconds being what they are, we will all be dead.