"There’s another – in some ways even bigger issue, and that is what is: the U.S. enforcement capability in the event that they violate the agreements," Ross told Fox Business Network in an interview.
"This is a long, involved process," he added.
On Tuesday, President Donald Trump said the United States still had a long way to go to conclude a trade deal with China, and said U.S. officials could still impose tariffs on an additional $325 billion worth of Chinese goods.
The United States could also face Chinese sanctions after a World Trade Organization ruling on Tuesday.
On Wednesday, a gauge of global stocks declined for a second straight session amid the concerns over U.S-China trade. U.S. Treasury yields also fell.
(Writing by Susan Heavey; editing by Jonathan Oatis)