Why The World Distrusts Russia
To understand why NATO became a reality and why the world is opposed to Russia's military invasion of Ukraine without provocation, we need to look at a couple of maps and the history of Russia/Soviet Union and Western Europe.
First, a map of Russia/Soviet Union after their revolution in 1917 showing the "new" Soviet Union in 1920.

You might notice that it didn't include all the nations in pink, although they were somewhat under the influence of the Soviets.
In the 1930s and 1940s, along came Hitler and WWll. It is indisputable that (a) Russian first made a pact with Hitler and stood by as he invaded Europe, but then Hitler, as he was wont to do, reneged on the pact and invaded Russia and (b) millions of Russian died in that conflict.
The resulting war was devastating to Russia and was at least due in part to Stalin not paying attention to what Hitler was up to; Stalin and the USSR were unprepared for war. History has documented the reign of Stalin, and it's not a pretty one.
Russia became deeply involved in WWll, and with the allied forces, defeated Hitler and Nazi Germany. The big difference was that, following the war, most countries were willing to return to within their borders, but not the Soviet Union. The U.S. and western allies did maintain a military presence to prevent any resurgence by the Nazis or any other like-minded group. Russia, on the other hand, having moved into Eastern Europe and countries like Belarus, Ukraine, Latvia, etc., decided to stay.
The new flag for the Soviet Union with the hammer and sickle was to represent the coming together of the farmers (sickle) and the workers (hammer) in the 1917 revolution that created the Soviet Union. Over time and with the militaristic attitude of the Soviet government under Stalin, the hammer and sickle took on new meaning to much of the world.
A war-weary Europe agreed with the Soviet Union to the Warsaw Pact. The Warsaw Pact, so named because the treaty was signed in Warsaw, included the Soviet Union, Albania, Poland, Romania, Hungary, East Germany, Czechoslovakia, and Bulgaria. The treaty called on the member states to defend any member attacked by an outside force and set up a unified military command under Marshal Ivan S. Konev of the Soviet Union. It might be noted that, under Soviet rule, any country like Hungary that rejected Soviet domination soon found its streets full of Russian tanks.
The rest of Europe, sensing a confident militaristic attitude by Stalin and the Soviet Union, formed NATO in 1949 with some of the remaining 12 countries from WWll, including Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, the United Kingdom, and the United States forming the original NATO. It committed the Allies to democracy, individual liberty, the rule of law, and the peaceful resolution of disputes. Over time, NATO would grow to include 18 more countries (some after the dissolution of the Soviet Union). Added countries were Greece and Turkey (1952), Germany (1955), Spain (1982), the Czech Republic, Hungary and Poland (1999), Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia (2004), Albania and Croatia (2009), Montenegro (2017) and North Macedonia (2020).
As a result of the Warsaw Pact and their desire to increase their global footprint, the Soviet Union set about wrapping the Warsaw countries into their Soviet flag, whether those countries liked it or not. The result was the following map (Fig 2)

The Soviets expanded their influence politically and militarily into all the countries shown in red and pink on this map. Some were annexed outright, and others designated as "satellite states" of the Soviet Union.
This voracious appetite for grabbing land, nations, and peoples of countries is the world had the cold war. The western world had watched the Soviets roll tanks and personnel into nations that resisted Soviet domination; the Soviet Union became the modern Roman Empire, or Mongolian Empire - pick whatever imperial period in history you like. They were ideologically in competition with democracy.
Following the collapse of the Soviet Union in 1991, countries in red and pink were freed from the imperial yoke of the Soviets and became independent once again. Many, if not most of them, rushed to join NATO to avoid once again becoming the puppet of a resurgent Russia.
For 30 years after 1991, Russia licked its wounds and began rebuilding its country while the rest of the world went forward with democratization and freedom. Gorbachev was forced from office. Brezhnev was president for a time, and then Putin came to power. August 1999 marks the beginning of now-President Putin's reign over the Russian people. He was appointed acting prime minister by former Russian Federation President Boris Yeltsin, who unexpectedly resigned soon after, making Putin acting president.
Putin claims that NATO has pushed democracy ever closer to the border with Russia. It may be true that the U.S. and NATO are champions of democracy, but no country that has ever joined NATO was forced to do so under the threat of violence of war. No tanks rolled into NATO countries, as we see happen in Ukraine. Every NATO country has joined NATO of their own accord, generally out of a fear that Russia would impose a military and political rule on them.
Russia has never shied away from using military might to bring countries like Georgia and several "Stans" to heel under their power. They are using that same aggressive approach to get Ukraine into their autocratic and oppressive tent.
Russia is under control of the old guard, the ex-communists who ruled the Soviet Union with an iron fist. While they changed the Russian flag to red, white, and blue after the collapse of the Soviet Union, the old hammer and sickle that came to mean more than just the workers and farmers still lurks in the shadows of the Putin regime.
