The way the strikes are being carried out has deepened suspicions that the United States has abandoned the goal of ousting Mr. Assad, according to several rebel commanders who have received financing from the United States, diplomats in touch with insurgents and activists, as well as dozens of residents of opposition-held areas inside Syria who were interviewed by telephone or electronic messaging.

And on Tuesday, Mr. Assad’s foreign minister, Walid al-Moallem, told The Associated Press that the government was “O.K.” with the attacks.

The Assad opponents said they were troubled by reports of civilian casualties, and by the targets the United States has struck, including several headquarters and commanders of the Nusra Front, an insurgent group not previously advertised as a target, deep inside territory it shared with other anti-Islamic State insurgents in Idlib Province. While the United States lists the Nusra Front, an affiliate of Al Qaeda, as a terrorist organization, it is considered a tactical ally by many Syrian rebels, including some of those the United States has deemed worthy of support.

There are also complaints about what has not been struck. In northern Aleppo Province, Islamic State militants have been carrying out a weeklong assault on a Kurdish area, where residents have pleaded for military aid.