The U.N. said Wednesday that 23 percent more Afghan civilians were killed or wounded in the first half of 2013 than during the same period last year, a finding that raises troubling questions about the Taliban's ability to terrorize Afghanistan as the U.S. military withdrawal quickens.

The U.N. Assistance Mission in Afghanistan reported 1,319 deaths and 2,533 civilians wounded, attributing most of them to the insurgency's increased use of improvised explosive devices and to firefights in which civilians are either targeted or become collateral damage. Casualties among women and children increased by 38 percent, the report said.

The sharp rise in casualties coincides with the first fighting season in which Afghan soldiers and police have been doing the bulk of the fighting. Those forces have also taken unprecedented losses. More than 2,750 police officers have been killed in the past four months, the interior minister said.