The United States says it is "horrified" by deadly Syrian regime air strikes on the Islamic State stronghold of Raqqa.
Activists say nearly 100 were killed in the Syrian bombing raid on November 25, about half thought to be civilians.
The U.S. State Department condemned the aerial strikes, saying the regime of Bashar al-Assad placed no value on human life.
"We are horrified by the reports that the Assad regime's airstrikes yesterday in Raqqa, Syria killed dozens of civilians and demolished residential areas," State Department spokeswoman Jen Psaki said in a statement.
Psaki said Assad had lost his right to rule, and said his actions should be held accountable.
The United States has built up a coalition of more than 60 countries in the fight against the Islamic States militants who have seized swathes of territory in Iraq and Syria.