We need to go back even further than those posts do.
Russia has been invaded over its Western border 3 times in modernity. The first was by Napoleon. The second was by a bunch of Western European nations. The third was by the Third Reich.
Every single invasion was bloody, but the first and third were devastating. Millions of Russians died fighting off Napoleon and millions died fighting off the Third Reich.
And both of those invasions followed the same route crossing into Russia in what today is the border between Russia and Ukraine.
It has been well established for centuries, therefore, that this specific area land is the most vulnerable spot of Russian national self defense.
So that's the first understanding that comes from history that is critical to our understanding of the present. The second is understanding how military campaigns like this work.
How did France invade Russia? What did Napoleon have to do? Well, take a look at a map and you'll see that it's not a short distance. The route goes through many sovereign nations. And we're not talking about just a bunch of soldiers walking to Russia and trying to cross a border. We're talking about a massive army. It requires supplies, which means it requires supply lines. It requires reconnaissance, communications, housing, ammunition, food, defensive positioning and fortifications, etc. This is no small feat. It's a huge undertaking. Napoleon enlisted a number of European countries along the route to support the campaign and historians study the logistics of this invasion very heavily.
How did the Third Reich invaded Russia? First, they made land grabs that were appeased. Then they invaded other countries. In both modes of expansion they built their logistics to support their military campaign of invading Russia.
Understanding the importance of logistics in these invasions gives us the background we need to understand NATO.
NATO is a military that was founded specifically to "counter" Russia. Among other things this includes plans for an invasion, because it has to. But unlike France or Germany, NATO is not a national military, it's transnational, and unlike any other anti-Russian army on the continent in history - it has nukes. NATO emerges just as all the great powers decide to stop warring amongst themselves and instead choose to fight proxy wars in the periphery. So NATO is a transnational nuclear military that forms in peacetime. And what does it do? It expands.
It gains land, money, soldiers, and sovereignty from other European countries as part of its treaty structure. It uses all of that to build a vast logistics network across Europe during peacetime. And it moves that logistics network ever Eastward towards Russia, eventually reaching Ukraine in late 2013 with the first ever joint NATO/Ukraine military exercise.
To Russia, this looks like a slow motion invasion. Which is made worse when we realize that the US worked with the Vatican to spirit away many Third Reich officers under Operation Paperclip, and then hand picked from among the Third Reich officers which ones would lead NATO. Yes. The US staffed NATO leadership with Nazis. Because Nazis were specifically oriented towards the invasion of Russia. It's made worse when we realize NATO conducted Operation Gladio where it established neo-nazi terrorist cells all over Europe as a contingency against Russian invasion. It's made worse when a supposed defensive alliance decides to bomb Yugoslavia for "humanitarian reasons" - the first ever war for humanitarian reasons - which included dropping DU bombs from airplanes into populated areas.
All of this history helps us understand the genuine national security threat that Russia is facing as part of a historical process, not merely a paranoid assessment or set of assumptions. And it helps us understand the rhetoric and logic of escalation since 2014 on both sides.
I encourage you to research the NATO exercises that involved Ukraine. It includes things like simulating and invasion of Kaliningrad and flying B-52 nuclear bombers in Ukrainian airspace.
All of this history fundamentally changes the framing of this particular conflict.