Pentagon reporter Tara Copp got rare access to see how the U.S. government and contractors maintain the highly classified U.S. nuclear arsenal.

The timely story came as U.S. military leaders warn that America has entered an uneasy era of global threats that include a nuclear weapons buildup by China and Russia’s repeated threats to use a nuclear bomb in Ukraine. To counter those rivals, the U.S. has a network of nuclear bombs and missiles that has not been overhauled since the Cold War.

Copp spent months convincing U.S. military officials to grant her access to sensitive U.S. nuclear labs, factories and missile silos. Supported by grant funding from the Carnegie Corporation of New York and Outrider Foundation, she hit the road, taking readers inside a constellation of highly classified bases and complexes. She showed readers how technicians labored over bombs and missiles. She climbed down into the sheer-drop tubes and watched as young airmen serviced the 70,000-pound Minuteman III intercontinental ballistic missile. The story resonated with readers. It tallied a 100% engagement score and garnered 45,000 page views.