Abubakar Shekau, the leader of Nigerian Islamist militant group Boko Haram, has claimed responsibility for the more than 200 schoolgirls that were abducted two weeks ago and vowed to “sell them in the market.” After pressure from the international community for the Nigerian government to act, the country’s president has reached out to the U.S., among other countries, for help finding and ensuring the release of the girls. Secretary of State John Kerry said on a trip to Africa that the U.S. will do all it can to help, and also took the opportunity to slam the jihadists for…not offering...