The good news is that the number of countries storing these dangerous materials has dropped from a high of 52 in 1992. The bad news is that increasingly well-organized and well-funded terrorist organizations—which now have easy access to the know-how needed to build a bomb— have declared their intent to seek the materials necessary for weapons of mass destruction.

Today, we work with governments to define, assess and improve nuclear materials security. A key effort: the biennial NTI Nuclear Security Index, a now-indispensible tool for governments.