Video surfaces of girls captured by Boko Haram

Hundreds of Nigerians marched through their country's major cities, angry that more than 200 schoolgirls still remain missing two years after their high-profile kidnapping by Islamic extremist group Boko Haram.

Thursday's march comes amid a growing recognition that Boko Haram is exploiting children not only to harm individual communities but also as a political tool. Their exploitation, while alarming, could actually indicate the military's offensive against Boko Haram is working.

Boko Haram used 44 children to commit suicide attacks last year, representing an elevenfold increase from 2014. The number of attacks overall also increased from 32 to 151. Attacks by children against "soft targets" such as public markets show the group has become more wary of direct assaults against the military, Josh Kenworthy wrote for The Christian Science Monitor:

[Boko Haram] is also keenly aware of the shock value of using children to commit violence. But Boko Haram may be deploying children against soft targets like local markets because the international coalition spearheaded by Nigerian President Muhammadu Buhari has become a harder target, and has had some success in liberating territory as well as captive women and children. And amid the gloomy statistics, there is evidence that young girls who have been radicalized or forced to carry out attacks can change course – even at the last minute.

Nigerian Vice President Yemi Osinbajo is expected to visit the hometown of the kidnapped girls, where he will likely meet with anger from parents whose children currently have no school.

Boko Haram firebombed the school in Chibok, Nigeria, when they kidnapped almost 300 girls two years ago. The school, which served about 20,000 children in Chibok and the surrounding area, has not been rebuilt.

"Boko Haram has achieved its aim," Yakubu Nkeki, who leads a group for parents of the kidnapped girls, told the AP. "They say they don't want us to have Western education and our children don't."

The march through Nigeria's cities follows the publication on Wednesday of a CNN video that showed 15 of the kidnapped girls, all wearing Islamic headscarves. CNN also released footage showing an emotional mother reach toward the computer screen when she saw her daughter among the kidnapped.

Negotiators working to free the remaining 217 girls received the video, dated Dec. 25, 2015, after they demanded "proof of life" from Boko Haram. Sources familiar with the negotiation process told the Associated Press the video is authentic.

The government of President Muhammadu Buhari has improved Nigeria's record for fighting the militant group and rescued many of the kidnapped women and girls it victimizes. Progress is more slow than hoped, but some may be seen by the group's strategic use of child suicide bombers, Mia Bloom, a communications professor at Georgia State University and author of multiple books on terrorism including, "Bombshell: Women and Terror," told The Christian Science Monitor.

"When these groups are losing – when they're losing territory in particular – one of the ways to project that they're relevant, they're strong, they're still a force with which to be reckoned, is to have these attacks," she said.

This report contains material from the Associated Press.