there was never any US/Russian partnership in Syria..After Russian air came in the closet was notification so as to "deconflict"
Obama bungled the Syrian and Iraqi conflicts so badly we will be reeling from it for years. 1st and foremost he should not have pulled every last troop out of Iraq and created a power vacuum for ISIS to thrive.
2nd, he should have backed what was a free syrian army. Instead we gave them next to zero support while Russia was able to prop up Assad and propel him back to power.