For nearly 20 years, NATO has been trying to help Afghanistan’s security forces become self-sufficient. Emphasis has recently been put on strengthening the country’s air force and commando units. Despite the efforts, Afghan soldiers regularly need foreign backup on the battlefield. Officials say it’s difficult to train troops and build a military that’s simultaneously fighting a war. Violent attacks across the country and a high casualty rate among Afghan forces underscore the precarious security situation. This series focuses on efforts to strengthen Afghan forces amid persistent conflict.