I have noticed a few commentators expressing concern about the dangers that might arise if a nation runs a persistent current account deficit. There have been suggestions that this area of analysis is the Achilles heel of Modern Monetary Theory (MMT). I beg to differ. A foundation principle of MMT is that to be able to freely focus on the domestic economy, the national government has to be freed from targetting any external goals – such as a particular exchange rate parity. The only effective way for this to happen is if the exchange rate floats freely. In this sense, the exchange rate is the adjustment mechanism for external imbalances.