Peter Bergen : The Washington Navy Yard shootings not an isolated incident . There has been a string of cases of veterans and young people attacking military targets . In addition to Monday 's attack at the Navy yard , 2013 has seen other deadly incidents involving insiders at U.S. military facilities . Bergen says it 's good that Defense Department is fixing flaws in security . Bergen : One issue that slipped through the cracks was status of security .
Peter Bergen : The Washington Navy Yard shootings not an isolated incident . There has been a string of cases of veterans and young people attacking military targets . Bergen says it 's good that Defense Department is fixing flaws in security . Bergen : One issue that slipped through the cracks was status of security .