loan as they were almost exclusively invested in US Treasuries, which assisted the US to engage the Soviet Union in an arms race which ended with the latter's bankruptcy, and at the same time, turned Japan into the world's largest creditor and the US the largest debtor, as well as swelled Japan's domestic debt (Japan sold its own currency to fund the buildup of dollar based assets). By end of 1980, foreign assets of Japan were about 13% of GDP but by the end of 1989 had reached an unprecedented 62%. After 1997, nations in East and Southeast Asia began their massive build-up of forex reserves, as their levels were deemed too low and susceptible to the whims of the market credit bubbles and busts. This build-up has major implications for today's developed world economy, by setting aside so much cash that was piled into US and European debt, investment had been crowded out, the developed world economy had effectively slowed to a crawl, giving birth to contemporary negative interest rates. By 2007, the world had experienced yet another financial crisis, this time the US Federal Reserve organized central bank liquidity swaps with other institutions. 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, and again in 2016 followed the commodities collapse, Mexico had warned China of triggering currency wars. Adequacy and excess reserves 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