The Taliban claimed responsibility for the attacks in Khost. Their spokesman, Zabiullah Mujahed, reached by telephone at an unknown location, said that 15 suicide bombers, equipped with machine guns and vests packed with explosives, with 30 militants backing them up, attacked the base on Monday night since it was one of the largest foreign military bases in Afghanistan. He claimed some of the bombers got inside the base and had killed a number of American soldiers and destroyed equipment and helicopters. This last claim was denied by General Azimi of the Afghan military.

The fighting in the district of Sarobi, east of the capital, Kabul, on Monday night involved an unusually large insurgent force and resulted in even heavier casualties. Ten French soldiers were killed and 21 wounded, a statement issued by the NATO force in Kabul said, making the fighting the most deadly for foreign troops in Afghanistan since fighting in 2005.

French troops have only recently taken over from American forces in the area, as part of the expanded French deployment in Afghanistan under President Nicolas Sarkozy.

In response to the attack, the French president announced that he would fly late Tuesday to Kabul. “In its fight against terrorism, France has been dealt a harsh blow,” Mr. Sarkozy said in a statement. “My determination is intact. France is resolved to pursue the struggle against terrorism, for democracy, and freedom.”