Nuclear weapons inspection poses a dilemma: how do you train inspectors to identify nukes without revealing top-secret information about how to build them? Spreading detailed nuclear weapons knowledge goes against the principle of non-proliferation, and many countries would object to letting inspectors from a body like the United Nations dig around inside their war technology. As James Acton of the Carnegie Endowment for International Peace writes: The problem seems as imponderable as Bilbo’s riddle to Gollum in The Hobbit: What have I got in my pocket? A state has a concealed object that it claims is a nuclear weapon.