> But the recollections of those involved aren’t always consistent. Roland Dumas, who served as the French foreign minister in 1990, would later say that a pledge was made that NATO troops would not advance closer to the territory of the former Soviet Union. But the U.S. secretary of state at the time, James Baker, has denied that any such promise was ever made – a claim that some of his own diplomats, however, have contradicted. Jack Matlock, who was the U.S. ambassador to Moscow at the time, has said that "categorical assurances" were given to the Soviet Union that NATO would not expand eastward.
Even if you deny that such a promise was made (and broken), you should be able to understand how having a hostile military alliance literally on your border is unacceptable and the US would never accept it were the tables turned. That's the point.
There are no good guys here. Go back to the Cuban Missile Crisis. There's a popular narrative of the US being provoked. But the truth is, the US instigated the Cuban Missile Crisis by deploying strategic nuclear weapons to Turkey (interestingly under the auspices of NATO, a "defensive" pact). Cuba was reciprocity. Those missiles in Turkey were quietly removed.