Philip Poel, CEO of Ember Technologies, brought a temperature-adjustable mug with him when he attended the hearing. He said the company's mugs were 100 percent made in China. Ember was founded in 2010 by Clayton Alexander, who holds more than 100 patents worldwide and is the inventor of the General Electric LED light bulb Infusion.

That prompted a USTR official to ask how he protected patents in contract manufacturing.

"If you've been through or had the chance to visit a factory that we manufacture at, when you come into those factories, no keys, no phones. No, it's very much a lockdown situation," Poel told the official. "So, they're protected through our vendor."

Chinese analysts pointed out that the ongoing US-China trade tensions are presenting significant risks for both Chinese and US businesses.

Zhou Mi, deputy director of the Institute of American and Oceania Studies of the Chinese Academy of International Trade and Economic Cooperation under the Ministry of Commerce, said increased tariffs have led to a five-month decline in China's exports to the US and reduced US exports to China for eight consecutive months.

The proposed US list for imposition of tariffs on about $300 billion worth of Chinese imports would cause US prices for cellphones generally to rise by 14 percent, according to research by Trade Partnership Worldwide, an international trade and economic consulting firm.

Uncertainty in tariff measures has also resulted in a wait-and-see attitude toward investment cooperation between enterprises in the two countries, Zhou said.