As the Taliban opened a new front this week in the Afghan war by attacking American-backed aid organizations in Kabul, negotiators for the group and the United States were meeting in the latest round of talks on ending the war. The Taliban has struck aid organizations sparingly in the past, making the attacks on Wednesday at the offices of CARE and Counterpart International even more stark. At least nine people were killed and 20 others wounded, Afghan officials confirmed. The death toll was nearly double initial reports. A Taliban spokesman, Zabihullah Mujahid, was quick to claim responsibility for the attack and to offer an explanation on Twitter: Counterpart International, which works largely on civic engagement projects, is American led and is financed primarily by the United States Agency for International Development. But neither Taliban nor American negotiators commented on the inherent contradiction in talking peace while attacking civilian targets. The Taliban had rejected pleas by the Afghan government and the Americans for a cease-fire during Ramadan, but they had promised to avoid civilian targets during the holy month. The blast on Wednesday from a vehicle packed with explosives ripped off the gate of Counterpart’s compound and scarred much of the city block. Among the dead were three Afghans who worked in the nearby offices of the American aid group CARE, which first established a presence in Afghanistan in 1961 and is one of the oldest humanitarian organizations in the country. Aid groups, the Afghan government and the American ambassador in Kabul, John R. Bass, criticized the attack, but the lead American negotiator, Zalmay Khalilzad, has remained silent. The most recent post on his Twitter feed, on Tuesday, described the food he had eaten on a recent trip to India. He did not mention the talks or the bombing. A spokesman for the Taliban’s negotiating team, Suhail Shaheen, said Mr. Khalilzad returned Monday to Doha, Qatar, where a sixth round of talks concluded on Thursday. The Taliban was unusually harsh in its rhetoric toward the main target of the attack, Counterpart International. The Taliban spokesman, Mr. Mujahid, said the group employed foreign advisers who engaged in “various aspects of brutality, oppression, terror and promotion of Western culture.” It also criticized the group for allowing male and female staff to intermingle. Although the car bomb breached the outer wall and gate of Counterpart’s compound and four attackers entered its buildings, none of its staff were killed, the group said; many had taken refuge in safe rooms. The attackers were killed by Afghan security forces; an elite police officer was among the dead. One Counterpart employee, who declined to give his name, said that the attackers at one point appeared to try to talk the employees into opening a safe room door. “We didn’t because when there is a big attack you can’t trust people, you don’t know who is friend and who is enemy,” he said. A logistics company across the street, RBT, was also damaged by the blast, and its guard outside was killed, according to an employee, Masihullah Malikzai. Nine others there were wounded. “I feel so hopeless,” Mr. Malikzai said. “Everyone leaves Afghanistan because they feel the government can’t protect us.” The initial blast killed three CARE employees at their offices, including a security guard, Safiullah Ebadi; a driver, Mohammad Waqif; and a technical adviser on education, Mohammad Asif Frotan, CARE said in a statement released late Wednesday from Atlanta, its American headquarters. Mr. Ebadi had just bought land for his family, with hopes to build a house. Mr. Waqif had worked for CARE for 22 years. Mr. Frotan left behind six children. “This attack reflects the increasing dangers of humanitarian work in conflict-affected countries such as Afghanistan and the unfortunate daily reality of violence for many Afghan families,” the organization said. The American and Taliban negotiators have reached a preliminary agreement on the withdrawal of American troops from Afghanistan in exchange for a Taliban promise to end its alliance with extremist groups like Al Qaeda, but Mr. Khalilzad has been unable to persuade the group to accept a cease-fire or talks with the Afghan government. The New York Times