In the past 5 years or so, Obama and the State Department have gone out of their way to try and "reset" the American relationship with Medvedev and later with Putin himself. In the past 18 months or so, the US has had two specific international incidents in which the WH felt America needs to be involved. First, the Syrian civil war on the pretext that Syria was using chemical weapons on their own people and the various video reports of dying women and children from what was thought to
have been Sarin Gas. US intervention wasn't welcomed and Russia has had an interest in keeping Syria intact.
Russia took the lead on negotiations backed by the US. Next we had the escalation with Iran and their alleged nuclear weapons program. Russian ties to Iran are fairly well known, and the US and Israel have a stake at not letting Iran create nuclear weapons as they already have a delivery system with their Safir rocket.
Russia again was the lead mediator with Iran on talks..
Then we get Ukraine and Crimea occurring right after (or during the Sochi Olympics). The WH was caught flat footed, with no real answer to a move by Russia to intercede in Crimea. The reset was over, and now Syria and Iran are held in the balance while Putin does what he wants to do. I can only conclude Putin dangled two things he knew the WH wanted (Syria and Iran) then sends forces to Crimea and now is using both of those situations to their advantage. The reset was a ruse. Now the US and Russia are
disagreeing on how to move forward with Syria, and the
Iran negotiations are now being used as a pressure point with the US.
It's clear the US was rope-a-doped by Russia and this was planned out well before any troops were moved onto the border of Ukraine.