Just what is the United States retreating from?

I have a problem with the way Mark Landler frames recent Obama administration diplomatic activity -- the scheduling of a Syrian peace conference as well as the interim agreeement with Iran:

At one level, the flurry of diplomatic activity reflects the definitive end of the post-Sept. 11 world, dominated by two major wars and a battle against Islamic terrorism that drew the United States into Afghanistan and still keeps its Predator drones flying over Pakistan and Yemen. 

But it also reflects a broader scaling-back of the use of American muscle, not least in the Middle East, as well as a willingness to deal with foreign governments as they are rather than to push for new leaders that better embody American values. “Regime change,” in Iran or even Syria, is out; cutting deals with former adversaries is in.

To call these initiatives "a broader scaling-back of the use of American muscle" seems to me a distortion of historical US foreign policy norms. Regarding Iran: when has the U.S. ever imposed military muscle to halt another country's (professedly peaceful) nuclear program?  It is only the bluster of the neocons -- the crew who blundered into Baghdad -- and of a Congress always eager to show fealty to Netanyahu that makes a preemptive strike at Iran seem like a kind of default response to that country's nuclear program.