When someone says "Putin didn't invade Ukraine until Biden became president", it is followed either by silence, or by endless rationalizations for Biden's foreign policy failures. Remember weeks ago, when morons at DU were praising Biden for calling Putin's bluff? Turns out, it was no bluff.
Look DUmbshits, it is simple: Obama as president saw Putin take Crimea. Trump as president saw Putin take nothing. Biden as president is seeing Putin take Ukraine. Get it? Biden could have kept Putin in check if he was half the foreign policy guru you imagine him to be.
He probably started planning this invasion soon after trump lost. Massing troops and equipment from across Russia's 11 time zones took months of logistics prep.
Err, Russia already has large numbers of troops stationed its four military districts, for exactly the reason you mentioned. He probably didn't need to move much, if anything, across the whole of Russia.
Morons.