Before Russia attacked Ukraine, there was no NATO treat that side. Before the war, vast majority (60-70%) of Ukrainians were against NATO: https://en.wikipedia.

Before Russia attacked Ukraine, there was no NATO treat that side. Before the war, vast majority (60-70%) of Ukrainians were against NATO: https://en.wikipedia.org/wiki/Ukraine%E2%80%93NATO_relations#Popular_opinion_in_Ukraine https://en.wikipedia.org/wiki/Ukraine%E2%80%93NATO_relations... NATO is already directly at Russian borders: Norway, Estonia, Latvia, and Lithuania. The distance between Moscow and closest point in Latvia is about 600 km = 375 miles. Between Moscow and closest point in Ukraine 460 km. Not a big difference. Finally, the Crimea is not the proper warm-water port for Russia, because Turkey controls the straights at the exit of the black sea, and Turkey is a NATO member state. The main reason why Russia attacked Ukraine is internal. The two countries are very close historically and culturally, and the number of immigrants is millions both directions. Ukrainians were able to forcefully remove their corrupt leader from power. This was extremely scary for Putin, as he knew he’s likely the next. He started the war to teach Ukraine a lesson, and to alienate Russians against Ukrainians so Russians will see Ukrainians as their enemy, not the role model.