When the Cold War ended fifteen years ago, we all felt that the world had become a safer place. Tensions lowered, nuclear arsenals were reduced, and the threat of nuclear war and Mutually Assured Destruction receded. In the time since, an economically strapped Russia has allowed its nuclear forces to decay, while the US pressed on with further upgrades to its weapons systems - and now this threatens to cause problems. In a pair of articles in Foreign Affairs (The Rise of U.S. Nuclear Primacy) and International Security (The End of MAD? [PDF]), Keir Lieber and Daryl Press warn that the imbalance is now so great as to allow the US to launch a disabling nuclear first strike with no fear of retaliation. And they warn that countries such as Russia and China could respond to this situation by beginning a new nuclear arms race.
The Russians, at least, seem to have got the message. They're currently deciding exactly what to do about it, but it seems certain that they will embark on a nuclear modernisation program of their own to reduce their perceived vulnerability. Which will encourage the US to expand its forces to maintain supremacy, which will in turn require the Russians to have even more missiles. It's not Dreadnaughts, but its the same stupid game: an arms race. And the effect will be to destabilise international relations at precisely the time we thought that such disputes between large countries were over. The only way out of it is by a massive, mutual reduction in weaponry through a new arms control treaty - but I can't really see the US agreeing to surrender its advantage anytime soon.