In their campaign against the opposition, the Syrians have been using helicopters, MiG jets and trainer aircraft to hit targets daily in the north, the east, the south and in rebel strongholds on the edges of the capital of Damascus.
"The aim of the airstrikes appears to be to terrorize civilians from the air, particularly in the opposition-controlled areas where they would otherwise be fairly safe from any effects of fighting," Ole Solvang of Human Rights Watch told The Associated Press.
More than 4,300 people have been killed since summer in such attacks that amount to "serious violations of international humanitarian law," and people who commit such breaches are "responsible for war crimes," the New York-based group said in the report, the most comprehensive study of Syrian air force operations in rebel-held areas since the beginning of the conflict. The U.N. estimates that more than 70,000 people have been killed in the civil war.
The Assad regime has significantly increased its use of air power since July, when the rebels captured territory in the north after an offensive, as well as last month after they seized their first provincial capital, Raqqa. The city is bombed almost daily.
Human Rights Watch said it inspected 52 sites in northern Syria and documented what it labeled 59 unlawful attacks by the Syrian air force in rebel-held areas.