Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff, appeared to contradict upbeat assessments by the White House last month that indicated Assad’s government had suffered a series of military losses and was losing control.

Although the long-term effect is far from clear, Pentagon intelligence has concluded for now that Russian air attacks, which began Sept. 30, and growing involvement by Iranian-backed forces have helped Assad’s military advance on several critical fronts and extend his grip on power.

“The balance of forces right now are in Assad’s advantage,” Dunford, who visited the region last week, told the Senate Armed Services Committee.

Citing the Obama administration’s continued failure to find a reliable military partner in Syria, Dunford said, “No one is satisfied with our progress to date.”