The Boko Haram kidnapping of hundreds of Nigerian schoolgirls follows years of "ineffective" U.S. policy and analysis that ignored the Islamist extremists' motives, one critic says.

"It took the U.S. far too long to recognize that this is a problem of international Islamist extremism and not simply a matter of disaffected youth angry about poor government services, as the administration stated after a particularly devastating church bombing by Boko Haram on Easter in 2012," Nina Shea, director of the Center for Religious Freedom at the Hudson Institute in Washington, D.C., told CNA May 5.

"Until November 2013 when the U.S. finally designated Boko Haram as a terrorist group, the U.S. was providing funding to neighborhoods that gave rise to Boko Haram militants on the theory this would compensate for poor government services," she charged.

"That was not only an ineffective policy, it was dangerous. It created financial incentives for more terror," she said, calling on the U.S. to enact policies to address "this brutal and spreading threat."

Nearly 300 girls, most of them aged between 16 and 18, were kidnapped April 14 from their boarding school in Borno, Nigeria's northeastern-most state.

Abubakar Shekau, leader of Boko Haram, has claimed responsibility for the abductions and has threatened to sell the girls into slavery, also threatening more attacks on schools.

Boko Haram, which means "Western education is sinful," launched an uprising in 2009 and hopes to impose sharia law on Nigeria. It has targeted security forces, politicians, Christian minorities, and moderate Muslims in Nigeria's predominantly Muslim north.

There are 276 girls still in captivity, while 53 escaped, the Associated Press reports.

The crime has drawn international attention to Nigeria.

Boko Haram's attacks have killed thousands since 2009; according to the BBC, they have killed 1,500 in 2014 alone. The U.N. estimates that the attacks have led to more than 470,000 internally displaced persons in Nigeria.

Shea said that Boko Haram has made Christians its "chief civilian target."

"It has deliberately blown up or otherwise destroyed dozens of churches, some filled with worshipers, and attacked numerous Christian villages and homes."

The U.S. Commission on International Religious Freedom reports that Boko Haram has attacked more than 40 churches since 2012. It attacked churches on Christmas Eve or Christmas Day three years in a row, from 2010 to 2012, and has called on Christians to leave northern Nigeria.

Shea, a former member of the U.S. religious freedom commission, noted the case of Adumu Habila, a man who survived a November 2012 Boko Haram massacre of all the Christian men in his village. He was confronted by Boko Haram militants in who told him that he could live if he converted to Islam.

"He refused and was shot through the head and left for dead," Shea said. "Against all odds, he survived and after extensive surgery… he is able to tell of his traumatic ordeal."

The U.S. recognized Boko Haram as a foreign terrorist organization only in November 2013, after a lengthy advocacy effort from human rights and Christian groups.

Various groups petitioning for this recognition had argued that the State Department was downplaying or denying Boko Haram's religious motivations. Emmanuel Ogebe, a legal expert on Nigeria with the Jubilee Campaign, said in November 2013 that this approach was "disingenuous" and an impediment to analyzing the group's threat.

Shea said the U.S. should devote "substantial intelligence resources" to finding the kidnapped girls and to assisting Nigerian forces' efforts to end Boko Haram's "terrorism."

"Boko Haram is becoming stronger and better armed with time, staging attacks further south in Nigeria and training terrorists to attack across its borders."

"We must double down on efforts with Nigeria's government to stop this group and those who fund and train it."

On May 6, White House spokesman Jay Carney said that a team of U.S. military and law enforcement personnel would be sent to aid the Nigerian government. The team includes experts in investigation, intelligence, negotiations, information sharing and victim assistance, but no armed forces are being sent, he said.

Secretary of State John Kerry said previous offers of U.S. assistance before May 6 had been ignored, according to the Associated Press.

The National Consortium for the Study of Terrorism and Responses to Terrorism's 2012 report ranked Boko Haram the second most deadly terrorist group in the world, surpassed only by the Taliban of Afghanistan.