TINOS, GREECE, Feb 14 (Reuters Breakingviews) - The prospect of mutually assured destruction (MAD) helped avert nuclear conflict during the Cold War. Hopefully, fear of the economic equivalent will do a similar trick when it comes to a showdown with China. Still, the shooting down of a suspected Chinese spy balloon, which has led to a breakdown in diplomatic relations, is a reminder that errors can happen. To see whether MAD will be enough to prevent war between America and China, look at just how disastrous such a conflict – which could be triggered by a Chinese invasion of Taiwan...