A suicide bomber killed 21 people, including three U.S. soldiers, at a checkpoint in a packed market in eastern Afghanistan on Wednesday -- the third assault targeting Americans in as many days.
The daily violence is threatening to undermine international hopes of an orderly hand-over to Afghan forces at the end of 2014. Although American officials stress successes in establishing pockets of governance in some areas, the east and south continue to be plagued by regular attacks and clashes.
Wednesday's attack took place in a marketplace in Khost, near the Pakistani border and about 90 miles southeast of the Afghan capital, Kabul.
The assailant approached on foot through the shops and taxi stands packed with people and then detonated his explosives as he approached Afghan and U.S. soldiers at a checkpoint, said Baryalai Wakman, a spokesman for the Khost provincial government.
Three U.S. soldiers and an Afghan interpreter were killed, according to American officials. A convoy in the area responded to the attack, said Maj. Martyn Crighton, a spokesman for NATO forces in Afghanistan.
Besides the interpreter, 17 Afghans also were killed, according to the Afghan president's office. Two were police officers and the rest were civilians, Wakman said. Another 32 people were wounded -- all civilians, he said.
In nearby Logar province earlier Wednesday, a roadside bombing killed three women and four children crammed into a wagon pulled by a tractor. Four men were also wounded in the blast on a road outside the city of Pul-i-Alam, said provincial spokesman Din Mohammad Darwesh.
The bombings came a day after militants carried out two attacks in southern Afghanistan, storming a NATO military base and attacking a police checkpoint. An unspecified number of U.S. troops were wounded in the attack on the NATO base, officials said.
Monday, three gunmen dressed in Afghan police uniforms killed one American service member and wounded nine others in Kandahar's Zhari district. Nearly 1,900 U.S. troops have been killed in Afghanistan since the war began more than a decade ago.