Eliana Johns hunts for nuclear weapons. She’s a senior research associate at the Federation of American Scientists, where her team uses open-source intelligence — or OSINT — to uncover secrets about countries’ nuclear capabilities and intentions. In fact, much of what we know today about China’s nuclear arsenal comes from her colleagues’ work, which used commercial satellite imagery to reveal that China is undertaking a massive nuclear buildup — at a pace far exceeding publicly available estimates from U.S. intelligence agencies.

In our conversation, Johns explains where OSINT has worked best and why greater transparency around nuclear weapons is essential for a more stable and peaceful world.

We recorded this live at the Carnegie International Nuclear Policy Conference.