From Classical economic theory, those who ignore the effects of long run trade deficits may be confusing David Ricardo's principle of comparative advantage with Adam Smith's principle of absolute advantage, specifically ignoring the latter. The economist Paul Craig Roberts notes that the comparative advantage principles developed by David Ricardo do not hold where the factors of production are internationally mobile. Global labor arbitrage, a phenomenon described by economist Stephen S. Roach, where one country exploits the cheap labor of another, would be a case of absolute advantage that is not mutually beneficial. In 2010, economist Ian Fletcher authored a significant work entitled, Free Trade Doesn't Work: What Should Replace It and Why, where he has supported a strategic approach to trade rather than an unconditional or unilateral approach.
Foreign-exchange reserves (also called forex reserves or FX reserves) are assets held by central banks and monetary authorities, usually in different reserve currencies, mostly the United States dollar, and to a lesser extent the Euro, the Pound sterling, and the Japanese yen, and used to back its liabilities, e.g., the local currency issued, and the various bank reserves deposited with the central bank, by the government or financial institutions.
Central banks throughout the world have sometimes cooperated in buying and selling official international reserves to attempt to influence exchange rates and avert financial crisis. For example, in the Baring crisis (the "Panic of 1890"), the Bank of England borrowed GBP 2 million from the Banque de France. The same was true for the Louvre Accord and the Plaza Accord. More recently, the Fed organized Central bank liquidity swaps with other institutions. During the crisis of 2008, developed countries authorities adopted extra expansionary monetary and fiscal policies, which led to the appreciation of currencies of some emerging markets. The resistance to appreciation and the fear of lost competitiveness led to policies aiming to prevent inflows of capital and more accumulation of reserves. This pattern was called Currency war by an exasperated Brazilian authority.
The IMF  proposed a new metric to assess reserves adequacy in 2011. The metric was based on the careful analysis of sources of outflow during crisis. Those liquidity needs are calculated taking in consideration the correlation between various components of the balance of payments and the probability of tail events. The higher the ratio of reserves to the developed metric, the lower is the risk of a crisis and the drop in consumption during a crisis. Besides that, the Fund does econometric analysis of several factors listed above and finds those reserves ratios are generally adequate among emerging markets.
Reserves that are above the adequacy ratio can be used in other government funds invested in more risky assets such as sovereign wealth funds or as insurance to time of crisis, such as stabilization funds. If those were included, Norway, Singapore and Persian Gulf States would rank higher on these lists, and United Arab Emirates' estimated $627 billion Abu Dhabi Investment Authority would be second after China. Apart from high foreign exchange reserves, Singapore also has significant government and sovereign wealth funds including Temasek Holdings, valued in excess of $145 billion and Government of Singapore Investment Corporation, valued in excess of $330 billion.
In a strict sense, foreign-exchange reserves should only include foreign currency deposits and bonds. However, the term in popular usage commonly also adds gold reserves, special drawing rights (SDRs), and International Monetary Fund (IMF) reserve positions. This broader figure is more readily available, but it is more accurately termed official international reserves or international reserves.