In 2004, on a dark morning in eastern Congo, Kathi Lynn Austin and a U.N. team conducted a surprise inspection at airfields infamous for arms smuggling. By evening, they’d uncovered critical links to international arms trafficker Viktor Bout—evidence that would lead to his inclusion on the U.N. asset-freeze list. Years later, Austin reflects on the relentless challenges of bringing arms traffickers like Bout to justice and on the need for a robust Arms Trade Treaty to prevent future atrocities.