When it comes to the spread of nuclear weapons, all paths lead back to the US, the New York Times reports in a look at two books. In The Nuclear Express, the authors chart the rise of the world's nine nuclear nations and conclude that "since the birth of the nuclear age, no nation has developed a nuclear weapon on its own." Soviet spies infiltrated the Manhattan Project, and the secret was out.
From there, Russia shared its knowledge with China—which led to one of the book's revelations: In 1982, China provided designs for a bomb "anybody could build" to Algeria, Pakistan, and North Korea. Pakistan enlightened Libya, which passed the info on to Iran, the authors say. But the author of The Bomb: A New History is hopeful politics can turn the tide. "Nuclear proliferation is not unidirectional," he writes.