Iran & US: "The US needs a reversal for Iran in Syria!"

"...For the United States, preventing the expansion of an Iranian sphere of influence is a primary concern. Iraq is going to be a difficult arena to stop Iran's expansion. Syria therefore is key at present. Al Assad appears weak, and his replacement by a Sunni government would limit -- but not destroy -- any Iranian sphere of influence. It would be a reversal for Iran, and the United States badly needs to apply one. But the problem is that the United States cannot be seen as the direct agent of regime change in Syria, and al Assad is not as weak as has been claimed. Even so, Syria is where the United States can work to block Iran without crossing Iran's red lines.
The normal outcome of a situation like this one, in which neither Iran nor the United States can afford to cross the other's red lines since the consequences would be too great for each, would be some sort of negotiation toward a longer-term accommodation. Ideology aside -- and the United States negotiating with the "Axis of Evil" or Iran with the "Great Satan" would be tough sells to their respective domestic audiences -- the problem with this is that it is difficult to see what each has to offer the other. What Iran wants -- a dominant position in the region and a redefinition of how oil revenues are allocated and distributed -- would make the United States dependent on Iran. What the United States wants -- an Iran that does not build a sphere of influence but instead remains within its borders -- would cost Iran a historic opportunity to assert its longstanding claims. ..."