Russia's Invasion of Ukraine: Military and Intelligence Issues and Aspects [Updated March 7, 2022] [open pdf - 985KB]
From the Document: "On February 21, 2022, Russian President Vladimir Putin announced [hyperlink] that Russia would recognize the independence [hyperlink] of two Russia-controlled areas in eastern Ukraine (the so-called Donetsk and Luhansk People's Republics [hyperlink], or DNR/LNR). Russian recognition appeared to include the entire regions of Donetsk and Luhansk, most of which had remained under Ukrainian control since Russia's first invasion of Ukraine in 2014. Shortly after February 21, Putin announced Russia would send 'peacekeepers [hyperlink]' into the DNR/LNR to defend against fabricated Russian charges [hyperlink] of Ukrainian plans [hyperlink] for invasion and sabotage attempts [hyperlink]. Despite denials from Russian officials, Russia had spent months amassing a significant portion [hyperlink] of its military capabilities [hyperlink] around Ukraine. The attack began after Russia had mobilized [hyperlink] between 150,000 and 190,000 [hyperlink] personnel on the Ukrainian border, in Belarus, and in Ukraine's occupied Crimea region, according to U.S. government estimates [hyperlink]. Russia's invasion follows months of warning and concern [hyperlink] from the Biden Administration [hyperlink], European allies, NATO, and some Members of Congress."
CRS Insight, IN11872
Congressional Research Service: https://crsreports.congress.gov/