NATO in Ukraine.
Russia is an enormous country, the largest on Earth, spanning 11 time zones and containing 11% of the world's landmass with an area of 17.1 million square km. It has enormous as yet undeveloped natural resources: minerals, trees, oil, gas, hydroelectric power.
And the Golden Million the global north countries that colonized, plundered, and exploited the global south for 500 years and feel entitled to continue doing this forever want those resources for themselves.
NATO in Ukraine would provide the West a platform on which to base missiles, aircraft, troops, intelligence paraphernalia, and everything else necessary to achieve the goal stated by U.S. officials to destroy the Russian state, cantonize Russia, and plunder its resources. This should come as no surprise. It is the way the West does business.
The U.S. always finds the most violent, hateful, sadistic, murderous monsters to groom, encourage, fund, arm, and train to carry out its coups and fight its proxy wars. This is also business as usual, as a cursory glance across the planet from Guatemala in 1954 to Afghanistan in 1979 to Syria in 2011 reveals. Using hyper-Russophobic Banderites to overthrow Ukraine's staunchly neutral president in an extremely violent coup in 2014 and launch a war of annihilation on Ukraine's ethnic-Russian population is U.S. standard operating procedure.
The Russian leadership are not idiots, and they are not warmongers. They have tried diplomatically since 2007 to keep NATO away from Russia's borders. This is not a question of "spheres of influence." It is a matter of existential necessity. NATO on Russia's borders means nuclear missiles aimed at Russian cities sited a few minutes flight-time away with the stated objectives by the U.S. listed in paragraph two above.
The U.S. is the modern-day equivalent of Napoleon, the Kaiser, and Hitler: a heart set on destroying the Russian state and taking control of its resources. There is no negotiating with this implacable aggressor, no matter how sincerely one engages. All the U.S. speaks are lies. Its word means nothing, and all it understands is raw, naked force. The only solution to this problem is regime change in Washington, its demilitarization and de-neocon-ification.
Fortunately, war against this marauding monstrosity can be fought on the economic front, and if that war is won and the U.S. does not lash out with nuclear weapons as its economy plummets into depression the world will be rid of it.
I rather expect an outburst of nuclear murder-suicide by the U.S. if at any moment it becomes indisputable in the minds of its leadership that their project to impose Full Spectrum Dominance on everyone on Earth is definitively and irretrievably lost.