ISTANBUL (AP) -- U.S. Secretary of State John Kerry on Sunday railed against the "cowardly" terrorists responsible for the attack that killed five Americans in Afghanistan, including a "selfless, idealistic" young diplomat on a mission to donate books to students.
In the deadliest day in eight months for the United States in the war, militants killed six Americans in separate attacks Saturday, the violence occurring hours after the U.S. military's top officer arrived in Afghanistan for consultations with Afghan and U.S.-led coalition officials.
The last American diplomat killed on the job was Chris Stevens, the U.S. ambassador to Libya. Stevens and three other American died in an attack Sept. 11 in Benghazi, Libya. No one has yet been brought to justice.
Kerry, in Turkey for meetings with the country's leaders, said 25-year-old Anne Smedinghoff of Illinois had assisted him when he visited Afghanistan two weeks ago. She served as his control officer, an honor often bestowed on up-and-coming members of the U.S. foreign service.
At a news conference with Turkey's foreign minister, Ahmet Davutoglu, Kerry described Smedinghoff as "a selfless, idealistic woman who woke up yesterday morning and set out to bring textbooks to school children, to bring them knowledge."
"Anne and those with her," Kerry said, "were attacked by the Taliban terrorists who woke up that day not with a mission to educate or to help, but with a mission to destroy. A brave American was determined to brighten the light of learning through books, written in the native tongue of the students she had never met, whom she felt it incumbent to help."
Kerry said Smedinghoff "was met by a cowardly terrorist determined to bring darkness and death to total strangers. These are the challenges that our citizens face, not just in Afghanistan but in many dangerous parts of the world -- where a nihilism, an empty approach, is willing to take life rather than give it."
The attack also killed three U.S. service members, a U.S. civilian who worked for the U.S. Defense Department and an Afghan doctor when the group was struck by an explosion while traveling to a school in southern Afghanistan, according to coalition officials and the State Department.
Another American civilian was killed in a separate attack in eastern Afghanistan, the U.S. military said in a statement.
It was the deadliest day for Americans since Aug. 16, when seven U.S. service members died in two attacks in Kandahar province, the birthplace of the Taliban insurgency. Six were killed when their helicopter was shot down by insurgents and one soldier died in a roadside bomb explosion.
Officials said the explosion Saturday came just as a coalition convoy drove past a caravan of vehicles carrying the governor of Zabul province to the event at the school.
A Taliban spokesman claimed responsibility and said the bomber was seeking to target either a coalition convoy or the governor.
Kerry said the terrorists only "strengthened the resolve of the nation, the diplomatic corps, the military, all resources determined to continue the hard work of helping people to help themselves."
He said "America does not and will not cower before terrorism. We are going to forge on, we're going to step up. ... We put ourselves in harm's way because we believe in giving hope to our brothers and sisters all over the world, knowing that we share universal human values with people all over the world -- the dignity of opportunity and progress," the Obama administration's top diplomat said.
"So it is now up to us to determine what the legacy of this tragedy will be. Where others seek to destroy, we intend to show a stronger determination in order to brighten our shared future, even when others try to darken it with violence. That was Anne's mission," he added.
The deaths brought the number of foreign military troops killed this year to 30, including 22 Americans. A total of six foreign civilians have died in Afghanistan so far this year, according to an AP count.
The Taliban have said civilians working for the government or the coalition are legitimate targets, despite a warning from the United Nations that such killings may violate international law.
In earlier remarks Sunday to U.S. consulate workers, Kerry said that "folks who want to kill people, and that's all they want to do, are scared of knowledge. They want to shut the doors and they don't want people to make their choices about the future. For them, it's you do things our way, or we throw acid in your face or we put a bullet in your face," he said.