The United States needs to keep modernizing its nuclear command and control system to combat possible spying from foreign company equipment installed in cell towers near its nuclear missile fields, the head of the U.S. Strategic Command said on Wednesday.

The comments come after he was asked about a Reuters report that the U.S. Commerce Department was investigating the national security threat posed by China's telecoms equipment maker Huawei, amid fears Huawei installations could capture sensitive information about the sites and transmit it to Beijing.

The previously unreported probe was opened by Commerce shortly after Joe Biden took office early last year, sources told Reuters, following the implementation of rules to flesh out a May 2019 executive order that gave the agency the investigative authority.

"We're well aware of potential threats to our Nuclear Command and Control. That's not new, right? The attractiveness of your opponent's Nuclear Command and Control has put it very high aspirationally for decades and we're well aware of that," Admiral Charles Richard, commander of the U.S. Strategic Command, told reporters.

"I have great confidence in the system, but I will point out that those threats that you're talking about are not static and we are going to have to continue to modernize our Nuclear Command and Control system to enable it to outpace those," Richard said.

He did not mention Huawei by name. A Huawei spokeswoman did not respond to a request for comment.

The Commerce Department subpoenaed Huawei in April 2021 to learn the company's policy on sharing data with foreign parties that its equipment could capture from cell phones, including messages and geolocational data, according to a 10-page document seen by Reuters.

The Commerce Department has said that it could not confirm or deny such an investigation.

Huawei has long been dogged by U.S. government allegations it could spy on U.S. customers, though authorities in Washington have made little evidence public. The company denies the allegations.