Secretary of State John F. Kerry pledged U.S. help Saturday in finding and returning hundreds of Nigerian girls abducted by militants more than two weeks ago.

“The kidnapping of hundreds of children by Boko Haram is an unconscionable crime,” Kerry said. “We will do everything possible to support the Nigerian government to return these young women to their homes and hold the perpetrators to justice.”

Nigerian authorities said more than 250 girls are still missing after the mass abduction of teenagers from schools on April 14.

Villagers and relatives of some of the abductees said some girls had been sold into forced marriages with their kidnappers, thought to be members of the militant Islamic movement known as Boko Haram. The group, whose name means “Western education is sinful,” has not taken public responsibility for the abductions.

“We are working to strengthen Nigeria’s institutions and its military to combat Boko Haram’s campaign of terror and violence,” Kerry said during a speech here on U.S. policy and objectives in Africa.

Protesters spoke out at the Nigerian embassy in Washington, D.C. to express their disappointment in the Nigerian government after an extremist group kidnapped nearly 300 girls on April 15th. (Jackie Kucinich/The Washington Post)

“I’ve seen this scourge of terror across the planet, and so have you,” Kerry said. “They don’t offer anything,” he said of movements such as Boko Haram. “They just tell people, ‘You have to behave the way we tell you to.’ Our responsibility, and the world’s responsibility, is to stand up to that kind of nihilism.”

Kerry did not specify what kind of help the United States could provide, but the abductions gave new urgency to efforts to boost the Nigerian government’s ability to counter the rebels.

A senior State Department official traveling with Kerry said later that Kerry was referring to security, communications and intelligence help for the overall fight against Boko Haram. The United States is not yet directly involved in the search for the missing girls, the official said.

“We don’t see this as just being a security problem,” said the official, who spoke on condition of anonymity to discuss the evolving strategy. “There are broader issues here that . . . relate to how the government works with people in these communities.”

A team of U.S. officials from several agencies will travel to Nigeria in the coming week for consultations, the official said.

Hundreds of women protested in at least three Nigerian cities this past week to express their outrage that the girls had not been found, the Associated Press reported.