The fear is that the companies' telecommunications equipment could serve as a backdoor for the Chinese government to spy on the United States, threatening the safety of American infrastructure.
Committee leaders Reps. Mike Rogers (R-Mich.) and Dutch Ruppersberger (D-Md.) have met with representatives from Huawei and ZTE in China and have also sent letters to their executives asking for further details about any of the companies' connections to the Chinese government.
So far ZTE plans to send Zhu Jinyun, a senior vice president at the telecom company, to testify next week. In a company statement sent to The Hill, ZTE emphasized that it "has achieved compliance with every important international and U.S. equipment standard" and said it has cooperated with the investigation by submitting "a series of factual responses" to the Intelligence committee.
"ZTE is the most independent, transparent, globally focused publicly traded company in China's telecom sector," the company said. "In its testimony, ZTE will demonstrate its unique ability to help provide solutions to cybersecurity issues pending before the Congress and the executive branch."
Huawei, on the other hand, will testify "once appropriate arrangements are agreed with the committee," company spokesman William Plummer said in an email.
"The integrity of Huawei’s operations and performance and the quality and security of our products are world-proven, across 140 markets," Plummer added. "Huawei is willing to share with the committee our understanding of global supply chain challenges based on our over 20 years of experience in the industry."
In particular, the Intelligence Committee leaders have questioned Huawei about its founder and president, Ren Zhengfei, and his previous service in the Chinese military.
In a somewhat unusual move this week, Huawei released a policy paper on cybersecurity that included a line promising that the company would not use its technology for spying or illegal purposes.
"Huawei does not, and would not support, condone or conduct activities intended to acquire sensitive information related to any country, company or individual, nor we do knowingly allow our technology to be used for illegal purposes," the white paper reads.
The committee officially opened this investigation last November.