The US is a perpetual war machine too (one might point out)? And yet there's Canada, not concerned in the least about being conquered and annexed by the dramatically larger and more powerful global military superpower to its south. And to the south, Mexico is actually invading the US more than the other way around; Mexico isn't much worried at all about the US invading and annexing its land. Russia's culture is different, it's still a power and conquest obsessed culture, it constantly dreams of greatness by empire in the old mold, and it still has a lot in common with the cultural beliefs of conquest that led to WW1 and WW2.
The Germans were similarly culturally obsessed with power, conquest and ethnicity, it's what Hitler swam in intellectually prior to his ascension to political power in Germany. The German people superstate was his dream. Putin even shares the obsession with ethnicity that Hitler did, he regards there as being a wholly bonded "Russian" people (as though the people in Kyiv or Moscow are connected to the Russian people in East Asia, and so on). In the mind of someone like Putin, anything can be justified in the name of that ethnic obsession, the notion of building / re-assembling a Russian ethnic superstate.
The reason Russia always behaves the way it does, is that it's a requirement of its very existence. If you remove their power and conquest lust, Russia will cease to exist. It would rip apart rapidly. The supposed Russian people superstate that Putin dreams of, is actually a lot of different peoples with little in common spanning vast territory (and obviously regionally the Russian people have a lot in common). It doesn't really exist as he imagines it. It can only be held together through the extreme use of force, because it's a nation that shouldn't exist. When something particularly shouldn't exist, nature will pull very hard on it (in relation to the extent to which it shouldn't exist), trying to take it apart (which is actually entropy grinding away on something hyper inefficient and difficult to order); and eventually, it won't exist, one way or another. Russia should be numerous nations and the next task for the West re NATO and Russia, is to see that that outcome is accomplished. Destablize Russia over the coming decades and see it broken into several new nations, just as the USSR was broken up before it. Putin won't live to see Russia split into several nations, but that outcome will happen this century. And that split outcome will be vastly better for everyone inside of Russia, it would greatly increase the potential for Western Russia (which would take the formal title of Russia) to become an affluent, peaceful state, no longer requiring the constant application of extreme force to just hold the state together (ie Russia would no longer have to govern in the model of always being afraid of its own people, dedicating its resources to oppressing those people, and could instead dedicate its vast resources to investing in its people and building prosperity). Huge sections of Russia would vote tomorrow morning to split off if they were freely allowed to.