You know, it was pretty clear that Russia was willing to go to war to stop Ukraine joining NATO. They said so multiple times since the first time the objective was announced, in 2008 I think, which was followed by the Russian war on Georgia for the same reason... and the annexation of Krimea also had the same root cause... so I am convinced the war could have been stopped, but the West made absolutely no effort to do so. Do you remember when Russia sent the "ultimatum" to the USA and the answer was that none of the Russian demands even merited consideration? They knew then that this response would lead to a war.
Therefore, I believe there's reason to believe the West willingly allowed Russia to enter this war, perhaps with exact this goal: causing Russia to go broke (similar to what happened to the USSR in Afghanistan, which was also assisted heavily by the West at the time) over a gigantic conflict (and sanctions), forcing a regime change in Russia, finally, at the cost of a totally destroyed Ukraine. Maybe the West thought the cost (thousands of Ukrainians and Russian dead, two destroyed economies, another generation of people who can't trust their neighbours anymore, increased military spending) was acceptable?
Therefore, I believe there's reason to believe the West willingly allowed Russia to enter this war, perhaps with exact this goal: causing Russia to go broke (similar to what happened to the USSR in Afghanistan, which was also assisted heavily by the West at the time) over a gigantic conflict (and sanctions), forcing a regime change in Russia, finally, at the cost of a totally destroyed Ukraine. Maybe the West thought the cost (thousands of Ukrainians and Russian dead, two destroyed economies, another generation of people who can't trust their neighbours anymore, increased military spending) was acceptable?