The Islamist militant group Boko Haram has conducted terrorist attacks in Nigeria that bring it closer to al Qaeda in northern Mali, making linkages between the groups more likely and more dangerous, according to a paper published by the Combating Terrorism Center. In the past year, Boko Haram has carried out several large-scale attacks across a 900-mile swath of Nigeria, roughly the distance between New York City and Atlanta, the paper states. That puts the Nigerian extremists just 300 miles from northern Mali, which is controlled by al Qaeda in the Islamic Maghreb (AQIM) and other affiliated groups. Boko Haram,...