American politicians and policy makers have blamed China's exchange rate for the large US trade deficits. This paper explains why the USA treats its trade deficits with China as a security issue that have become a source of friction in Sino-US relations. The essay argues that this friction is a useful deflection from the politically difficult policy action needed to remedy the US economy and cannot easily be removed by the Chinese side alone. The structure of global trade and the reality of China's political economy, which forces Chinese leaders to develop policies for a "harmonious society" in the face of growing inequality also makes it difficult for China to respond positively to US pressure on the exchange rate.