The deadliest weapon in the world today is not a nuclear bomb or an infectious agent, but a machine gun. Small arms kill half a million people a year, picking off American soldiers in Iraq, turning Liberian thugs into powerful warlords and allowing 12-year-olds in eastern Congo to terrorize their neighbors. The ease of obtaining AK-47's helps turn grievances into wars. Controlling small arms is complex. Guns are easily concealed, trading and retrading in a quasi-legal netherworld. ... THIS IS AN EXCERPT