U.S. military officials are arriving in Nigeria today to help in the search for hundreds of kidnapped schoolgirls.  Islamist militants who abducted nearly 300 girls have said they'll sell them as slaves.  The Americans working out of the U.S. Embassy in Abuja will provide expertise in intelligence, investigations, and hostage negotiations. Members of the Boko Haram militant group kidnapped the girls from a school in northeastern Nigeria more than three weeks ago. 

First Lady Michelle Obama took to Twitter to show her support for the missing girls.