Putin took the opening that Obama created for him.
At best, Obama created it as a naive act of goodwill. (In 2009, Obama canceled the tougher course Bush had put in place as a result of Putin's take-over of Ossetia and Abkhazia.)
Obama entreaties to Iran will have the same effect.
Obama's acts are nothing more than appeasement, and appeasement of our foes always results in adventurism by our foes.
We can expect more gambits from Putin - and soon from Iran, and China and North Korea and Syria and Lebanon - until the USA and the West make some credible counter-moves - and that means doing something much more substantial than enacting sanctions of any kind, targeted or blanket.
We don't have to go kinetic - yet. We do have to improve our ability to do so, and that means deploying defensive and offensive weapons in a way that more effectively focuses them on Russia (which means undoing Obama's Russian Reset).
And it means isolating Russia and Iran from the global economy.
To do that the USA and Europe need to increase production of energy.