The core argument is nonsense and bears little connection to actual events or motivations. Mearsheimer completely ignores the many nations of Europe, their history and current goals. He reduces the complex web of relations that goes back many centuries into an imagined US vs Russia confrontation that never was. He doesn't even speak Russian, which limits him to a tiny sliver of knowledge published in English. It's like a blind man trying to act as an expert in visual arts.

There is no such thing as "NATO expansion". At the end of the WWII, the USSR rolled over the entire Eastern Europe while fighting Germany. After the war ended, they refused to leave, and instead set up Moscow-controlled dictatorships that lasted until the USSR collapsed. I was born in one of such. Couldn't travel nor read foreign books. Didn't have freedom of speech and other most basic rights. An inappropriate joke could get you jailed. I personally knew someone who was sentenced to a Siberian labor camp in the 1980s for advocating human rights. Economy stagnated severely and shops were empty all the time. People had money, but there was nothing to buy in stores. Even top scientists and engineers had to grow their own food on small plots to feed their families. Bananas and jeans were considered rare luxury items.

The shithole finally collapsed in 1991 and Russia was forced to end their military occupation: pack up their dictatorship, dismantle the oppressive secret services and remove their armies. We were finally able to live as free Europeans again after 50 years. Visit other countries, read and write whatever we wanted.

And to ensure that we would never see the return of Russia, we tried to get as deeply integrated with the rest of Europe as possible. That means membership in the Council of Europe, European Union, and NATO.

Eastern Europe's entry into NATO and other organization was motivated purely by the extremely traumatic post-WWII experience of living under the Russian boot. It was our strong initiative desire to join the organization, against cold reception of existing members who had no interest in extending their defence pact. Ironically, they accepted us only because they believed our fears to be unfounded, meaning that they would never actually have to help us fight Russian invasions onto our soil, but saw value in the stabilizing effect that being in NATO would have.

NATO is not a threat to Russia, because NATO mandates civilian oversight over military affairs, and the mutual defense guarantee acts as a moderator that forces every member to consult with others before any military actions. This makes NATO countries extremely stable and predictable. We can see this clearly with aiding Ukraine, where every step is discussed for months and telegraphed long in advance. The over-reliance on stronger members of the organization, namely the US, has led to most European members to being unable to defend even their own country. Who in their right mind calls such countries a threat?

Russians unaffiliated with the dictator Putin understand this perfectly. The man who was Russia's foreign minister for most of the 1990s decribes NATO as "providing free-of-charge security along Russia's western borders". They have no problem with NATO and they are remarkably supportive of it.

The only ones raging over NATO are Putin and his cronies who have destroyed all opposition and consolidated all power in Russia and have now set their sights on external expansion through conquest. NATO stands in their way. They can't invade small countries one by one, but must face the entire bloc at once. They are unable to handle such a confrontation, hence their impotent rage.