This is interesting and very recent (3 days ago)
https://www.chinalawblog.com/2019/0...om-china-where-have-all-the-dollars-gone.html
.......Chinese would-be investors in U.S. ventures are finding it exceedingly difficult to get money out of China, even their allotted USD $50,000 in foreign currency each Chinese national is permitted to transfer out of China, according to China’s State Administration of Foreign Exchange. But in practice, such applications are being more closely scrutinized by China’s ever-present bureaucratic machine, and even China’s elites, like the former central bank adviser, Yu Yongding, are being denied access to foreign currency. That means your prospective Chinese investor or business partner (or customer who owes you money for your raw inputs, such as U.S. timber) may not be able to get you those U.S. dollars you have been waiting for any time soon, no matter how well connected they are.
Why is China holding onto U.S. dollars? China needs to maintain its foreign exchange reserves (largely held in dollars) for several reasons. One of the primary reasons is so China can continue to fund its global export machine that does business in U.S. dollars with the rest of the world. Chinese exporters buy their raw inputs in U.S. dollars, so China’s central bank needs to keep sufficient foreign exchange reserves to facilitate those transactions. A second reason is that to the extent China can keep U.S. dollars out of circulation, China can artificially keep its currency value low against a stronger U.S. dollar, which makes its exports more affordable to the U.S. and to the rest of the world. China holds more than $3 trillion in of its assets in a foreign currency, which equals approximately $2,142 per capita in China’s 1.4 billion population (in comparison, the U.S.’ $126 billion in foreign exchange reserves equals approximately $385 per capita in the U.S.’ 327 million population). China’s currency restrictions are not new. These restrictions are an integral part of China’s economic policies under which China wants to keep its yuan valuation at 7:1 compared to the U.S. dollar. China can also use its foreign currency holdings to buy up yuan when others are trying to dump it, to keep the yuan from freefalling in foreign exchange markets due to concerns like a trade war or ongoing economic restrictions or sanctions.....