> I can understand, if not sympathize with, their reaction as Western powers have established footholds in bordering countries.

That is a wrong way of thinking about NATO for several reasons:

1. Eastern European countries were not in the USSR or their satellites by their own choice. They were conquered and enslaved by Russians during the WWII. "Bloodlands: Europe Between Hitler and Stalin" by Timothy Snyder is an excellent book on how Eastern European nations fared as German and Russian war machines rolled over them. Russians raped, murdered, pillaged - and then for 50 years forced to play a happy family together under USSR's umbrella.

2. After USSR's demise, the initiative of joining NATO came from the countries in Eastern Europe that had restored their independence, to prevent the return of Russian rule. Western countries were extremely reluctant to extend their mutual defence pact to Eastern Europe. Western politicians underestimated Russian threat and dismissed Eastern European fears of another Russian invasion as a historic trauma.

Eventually, NATO membership was used as a carrot to boost reforms (such as civilian oversight over military structures) in Eastern Europe to ensure internal stability and avoid potential internal conflicts overspilling into western countries. The wars in Caucasus and Yugoslavia were a cautionary tale.

3. "Western powers" do not have a single military base in any country neighbouring Russia in Eastern Europe. Acceptance of Eastern Europe into NATO was not followed by any permanent deployment of Western troops or weapons.

The military balance in Eastern Europe has always been and remains heavily in favor of Russia. They have hundreds of thousands of soldiers, countless tanks, artillery systems and missiles, both conventional and nuclear, right on the border with NATO, and even within (Kaliningrad). Facing them is only light infantry, predominanty local and consisting of non-professional conscripts (think: National Guard), with insignificant number of Western soldiers serving as a tripwire for nuclear response.

Russian apologists would make you believe that NATO has buzzing army bases on the border with Russia, with soldiers waiting for a signal to run to their tanks or launch their missiles, but there's not a single such base. None. Zero.

4. The real threat to Russia aren't tanks and guns, but prosperity without Russia. Prior to the initial Russian invasion in 2014, Ukraine was on the verge of signing a favorable deal that would've opened up European markets to Ukraine. Imagine doing the same job, but earning two, three or even four times as much. Russia has nothing comparable to offer, yet they have a delusional belief that they should dominate neighbouring countries. Since Ukraine was slipping away from their influence, they first tried to bog Ukraine down by dragging it into a frozen conflict in 2014. When that didn't work out and only pushed Ukraine closer to the EU and NATO out of sheer necessity, Russians attempted a direct full takeover of Ukraine in 2022.

That failed too, and only accelerated the loss of influence. Ukrainians will not forgive the war as long as the generation of kids that spent their formative years hiding in bomb shelters from Russian missile attacks lives. Other countries, like Kazakhstan, are also increasingly looking towards the EU or China. Russian influence is crumbling fast. They simply have nothing to offer, and lash out violently whenever they can.

Essentially, these are aftershocks of the collapse of Russian colonial empire. Putin's era is characterized by impotent attempts to subjugate neighbours and restore the former empire, but with a military that is a shadow of its former self, and an economy barely half of California's.

It's not security that they are looking for. They want domination.