President Trump has been and continues to be upset with the Fed because the dollar continues to gain strength against other currencies, and he feels the Fed should react. That strength hurts U.S. exports and helps imports thus weakening his hand in his trade war with China. It also dampens exports to other countries especially when they are lowering their interest rates.
China’s currency continues to fall as their economy slows, but do not think China is supportive of a falling Yuan. They are fully aware that Trump thinks they are a currency manipulator and he may slap more tariffs on exports as a result, while at the same time they are dealing with a weak economy. Also, and maybe more importantly, they are worried about capital outflows from China. As their currency weakens, Chinese businesses and people want to move their money and investments offshore and that also puts strain on their economy.
The Euro is at a two-year low and the Ecb is slow to react, another Trump issue. Then of course he thinks our Fed is too slow as well. He wants the Fed to speed up lowering rates trying to put downward pressure on the dollar as it is gaining strength against all major currencies.
It is not a simple matter, but the Fed is likely behind in its efforts as we see our own economy showing signs of weakness. We may see the trade war morph into a currency war. The two are closely related.