This wouldn't have happened under Trump. Check out Jimmy Dore's coverage with Max Blumenthal. The MSM is lying to us about what's been going on. Jimmy explains it well. Scott Ritter also explained it well last night to Richard Meshurst. The Ukrainians are not the good guys here (we're talking actual neonazis)... The Russians not really good guys either but that's not relevant to their action in Ukraine. It's mostly pipeline security and a reaction to ongoing "Ukrainian" violations of Minsk accords. In this context, Putin's actions make prefect sense. FWIW Securing Chernobyl also makes sense for a superpower trying to keep Germany supplied with natural gas in the winter (see Texas blackout for an example of what happens to a modern gas dependent grid that loses power in the winter...The gas freezes in the pipelines). Keep in mind 40% of the German energy supply flows through Ukraine. The US doesn't like that so we destabilized the Ukrainian government under Obama... This stupid game stopped under Trump who thought this was crazy and pointless AF... Biden flunkies reinstated the insane policy of guerrilla terrorism by azzov battalion in the "separatist" regions (aka a region of ethnic Russians and Slavs that separated AFTER the CIA backed coup installed a psychopathic neonazi regime it couldn't control and was more concerned with ethnic cleansing than US/EU economic interests... ). Bottom line this was all about trying to force Europe and Germany to buy more expensive liquefied Texas fracked shale gas in the north and Quatari/Saudi gas via a pipeline that was supposed to transit Aleppo in Syria through Turkey in the south (hence that lost war) instead of Russian pipeline gas coming through Ukraine and Nordstream2... Most Germans including industrialists favor the more economically efficient trade with Russia, the World Economic Forum Neoliberal smooth brains (aka the German/French financiers etc + EU) get their funding from the Arabs (ie Saudis) and are kept on a tight leash. It's a clustertruck... This isn't west v Russia its western Neoliberals + arabs vs western conservatives (aka ppl who make stuff vs ppl who outsource production to our adversaries).
Sources: See the coverage by max Blumenthal and Aaron Matte at the Grayzone. See Glenn Greenwald's coverage of the Syria conflict. See Abby Martin's coverage of the various proposed Syria pipelines (Russian, Iranian, Qatari, Saudi, US during and following GWoT). For deep background that's accurate and compelling take a look at Confessions of an Economic Hitman and other books edited or written by Perkins. For the US policy look up statements by Gen W. Clark on the plan for Iraq, Syria, Libya, Tunisia, etc following 911. For corroboration from Bush cronies prior to 2000 see the infamous PNAC declaration. For more info on exact details are the coverage of wikileaks diplomatic cables discussing the disposition of Ukraine following the coup specifically the famous statement by senior spook in the region "screw the EU", referring to disrupting Germany's energy interests in Ukraine/Russia. To learn how this fits into long term US policy read The Devil's Chessboard (by either Dave Talbot or Don Fulsom can't remember which) and (the super boring) Globalization and it's Discontents by Stiglitz. This stuff is all very well documented but few people pay attention until it flares up into a crisis.