"China, the European Union and others have been manipulating their currencies and interest rates lower, while the U.S. is raising rates while the dollars gets stronger and stronger with each passing day - taking away our big competitive edge", Trump complained in one tweet.
The yuan fell to 6.7943 per dollar by late morning on Friday, down 0.28 per cent, according to Bloomberg data, and is at its lowest levels in a year following an accelerating slide in recent weeks as the trade conflict heated up. He imposed them on US$250 billion worth earlier this month.
"For that to change we'd need the Fed to back off its tightening policy or for tightening to begin to happen in Europe and Japan and I don't see either of those happening", said Stephen Massocca, Senior Vice President at Wedbush Securities in San Francisco. "We don't like what you're doing'".
What is a currency war?That makes it more attractive for investors to hold United States dollars, prompting them to sell other currencies. But currency devaluation also makes imports more expensive. "That hurts consumers and adds to inflation".
"The US does not mean to contain China", the official said. More than 70 per cent of Republican and Republican-leaning USA adults believe increased tariffs between the United States and its trading partners will be good for the country, according to a Pew Research Centre survey.More news: Jet Airways places order for 75 additional 737 Max aircraft from Boeing
Analysts say it's unlikely that China would use the weaker yuan as a weapon in the trade war.
The Chinese government has let the yuan weaken by around 4% against the dollar in the past month, among the sharpest one-month drops in value in its history.
In a taped interview with the business channel CNBC aired early Friday, Trump said "I'm willing to go to 500", referring roughly to the $505.5 billion in goods imported past year from China. That could in turn boost an economy that posted its slowest growth rate in almost two years - 6.7% - in the second quarter.
However, it is a high-risk strategy.
World stock markets fell sharply after Mr. Trump's remarks.More news: Vietnam tries American detained during nationwide protests
"By running tight monetary policy and loose fiscal policy, Trump has put nearly flawless conditions in place for a rally in the dollar", said Karl Schamotta, a strategist at Cambridge Global Payments in Toronto.
In a break with the usual practice by USA presidents, Trump has been unusually vocal about the dollar, publicly criticizing its strength several times, though analysts question whether his frequent rhetoric will have a lasting impact.
"I'm not doing this for politics, I'm doing this to do the right thing for our country", Trump said on CNBC.
While the Federal Reserve is raising short term interest rates in the face of consumer price inflation running at 2.9% annually in June, longer term bond yields may rise to attract foreign capital to finance the wider fiscal deficit and in turn keep the United States dollar strong.
The yuan's depreciation stems from a confluence of factors including the trade war, expected slower Chinese economic growth, and speculation that Beijing will take stimulus steps as a buffer, which tends to pressure a nation's currency.More news: Pompeo, Haley call out China, Russia for helping North Korea violate sanctions