Citing people familiar with talks, Bloomberg recently reported that President Donald Trump's threats on Twitter came after his top trade negotiator told him that China in last week's talks had backed away from earlier commitments. 

"In talks last week in Beijing, Chinese officials told their U.S. counterparts they would not agree to a trade deal that required changes to Chinese law, the people said. China had previously agreed to change its laws in the text of the deal, they said," Bloomberg wrote.