Much of the interview’s resonance is in its timing, coming two days after Mr. Obama authorized airstrikes against Sunni militants in Iraq. Mrs. Clinton’s aides say this was an unfortunate coincidence; the session was scheduled before anyone knew about military action, which has “amplified a statement about militants” she has made before.

Still, when Mrs. Clinton says that “the failure to help build up a credible fighting force” against President Bashar al-Assad in Syria “left a big vacuum, which the jihadists have now filled,” the suggestion is that Mr. Obama’s refusal to arm the rebels might end up being a singular misjudgment. But at the time of the Obama administration’s internal debate over that decision, several officials said, Mrs. Clinton’s advocacy was far less thunderous: The United States had tried every diplomatic gambit with Syria, she said, and nothing else had worked, so why not try funneling weapons to the moderate rebels.

As Mrs. Clinton stakes out her own foreign policy positions in advance of a possible campaign for the White House, it is only natural that some of her statements will not be entirely in sync with her record as secretary of state, when she served at the pleasure of the president.

At the end of her tenure, for example, Mrs. Clinton wrote a memo to Mr. Obama recommending that the United States lift its half-century-old trade embargo against Cuba. It was not a position that she seriously advocated while at the State Department, officials said.

In the interview with The Atlantic, Mrs. Clinton said she had always been in the camp of those who believed that Iran had no right to enrich uranium. Yet in December 2010, she was one of the first American officials to acknowledge publicly, in an interview with the BBC, that Iran could emerge from a nuclear deal with the right to enrich.

Mrs. Clinton also lined up solidly with Prime Minister Benjamin Netanyahu of Israel — a starkly different position from the first term, when she often had to play the heavy during peace negotiations, chiding Mr. Netanyahu for refusing to curb settlement construction.

Even on the Gaza conflict, about which the State Department harshly criticized Israel recently for the number of civilian deaths, she said, “I’m not sure it’s possible to parcel out blame” because of the “fog of war.”