It happened in plain sight: a relentless accumulation of troops, tanks and rockets that took place over nearly four months and was captured by ordinary Russians on their cellphones and dashcams, as well as by commercial and spy satellites.
U.S. President Joe Biden warned as far back as Jan. 19 that Russian President Vladimir Putin would "move in" on Ukraine. By Feb. 18, he was convinced that Putin had decided to invade within days and attack the capital Kyiv.
But frantic diplomacy, sanctions threats and unprecedented U.S.-led "information warfare" proved powerless to prevent what finally unfolded in the early hours of Thursday, as Russia's missiles struck Ukrainian cities and its troops poured across borders.