So check this out:

Russia was trading with England when Napoleon, Emperor, decided to blockade England. Russia continued trading with England despite Napoleon's demands to stop, so Napoleon built an army and marched it all the way East across Europe. It invaded Russia across the Ukraine border, because it was the strategic weak point of Russia, and that war is considered one of the bloodiest campaigns of history. Millions of Russians were killed. Russia won, but at great cost.

Years later, the Third Reich emerges in Germany. Hitler wrote a book about the communists being the biggest threat to Europe's way of life. He claimed he would invade Russia and make all of the slavs live on reservations like the Americans did to the indigenous peoples, create an apartheid state like the Americans did to the blacks, and build the new continental European empire with the spoils of war. He built an army and marched it all the way East across Europe and invaded Russia over the Ukraine border, because it's the strategic weak point. It was a terribly bloody invasion. Millions of Russians died. Russia won, but at great cost.

After the Russians defeated the Third Reich by marching all the way to Berlin, defeating 80% of the Nazi military, the USA nuked two Japanese cities with large civilian populations, and then took over the Korean peninsula from the Japanese empire, where it proceeded to bomb the half of Korea that was adjacent to Russia to the point where there were literally no more structures and Koreans were living in caves. The USians built NATO and staffed it with the same Nazi officers that just went on the war path to invade Russia, and the USA worked with the Catholic Church to save many Nazis officers and give them safe haven throughout the world via Operation Paperclip. Through NATO they also built a vast network of "leave behind" armies that were built around Nazis and Nazi sympathizers across Europe that they could activate as resistance fighters if Russia ever invaded - Operation Gladio. They build a vast network of proxies through which they fomented uprising, coups, and what we now call "color revolutions" to threaten the USSR. And most importantly for this conversation, they not only launched a bunch of proxy wars with the USSR through various proxy states but they also built a transnational nuclear-armed military in Europe that had no democratic accountability to any people. Using this transnational nuclear military they deployed nukes everywhere in Europe aimed at Russia.

In 1992, after the dismantling of the USSR, Russia met with NATO and Bill Clinton to talk about how to maintain peace now that the USSR was gone. The Russian position was that Russia's national security could not be considered separate from Europe anymore, like the Iron Curtain strategy position, so Russia committed to building mutual security. One aspect of that mutual security was for everyone to respect MAD and not make attempts to create nuclear first strike capabilities. Another aspect of that mutual security was that Russia needed to protect the Ukraine border, over which it has been invaded multiple times before with great loss of life. There was a discussion about not expanding NATO Eastward for 2 reasons: 1) because putting nuclear capabilities around Russia is a component of undermining MAD and 2) putting an army on the Ukraine border made it possible to invade Russia again.

NATO made statements about not expanding Eastward, but no firm doctrinal commitments. And when they did expand Eastward, Russia didn't fight back. They appeased the West as they built nuclear capabilities all along Russia's Western border. They appeased the US when the USA funded neo-nazis and terrorists. The USA vetoed every vote to condemn the celebration of Nazis, but Russia just took it. And that's their choice. So we don't need to bother with it.

But Bill Clinton said that NATO will never be in Ukraine back in 1992 directly to Russian leaders, and as soon as that meeting was over he told his military staff to start building a plan to get NATO into Ukraine.

For the last 30 years that's the context that Russia has been dealing with. Starting with Bill Clinton taking NATO and saying it's a defensive alliance only and then proceeding to use it to devastate Yugoslavia, the last socialist state in Europe. This defensive alliance dropped depleted uranium bombs from aircraft into civilian cities. They destroyed Yugoslavia with a defensive, while Russia was listening to the empty promises of Bill Clinton and NATO ringing in their ears.

In 2014, when there was a coup in Ukraine, it could have just been some standard political unrest. But John McCain and Victoria Nuland were literally in Maidan Square. John McCain was on stage with Right Sector saying it was a great day for democracy. Victoria Nuland was caught in tape discussing who would be the next president of Ukraine. And the day after the Ukraine government agreed to work with the protestors demands, the Right Sector stormed the capitol with guns drawn, forcing the sitting president and government to flee the country.

Russia correctly saw this as a US-guided situation that was part of the historical process of eventually bringing Ukraine into NATO to fully encircle Russia and break it's national security. So it reacted and invaded Crimea. After Maidan, Ukrainian neo-nazi militias that were tied to the history of Operation Gladio began killing ethnic Russians in Ukraine, with back channel US support.

And in 2022, Russia said they saw military activity on the border, significant enough that it could not be ignored anymore. Was it missile systems? Was it missile defense? Was it rapidly deployable units? We won't know until the dust settles, but Russia invaded and this was it's stated reason.

You can keep pretending that Russia invaded Ukraine for resources, but Russia has never had any intention of invading and holding all of Ukraine. In the assessment of the CIA, not only does Russia not have the capability to do so, it knows it doesn't have the capability to do so and the CIA has clearly identified that it has never been a strategic goal of Russia to do so.

The real reason has everything to do with national security, and if you study history, it becomes painfully obvious that this is the case.