The U.S. government is years behind China in the pursuit of so-called hypersonic weapons that bob and weave through the atmosphere at more than five times the speed of sound, Raytheon Technologies Corp.’s chief executive officer said Tuesday.

While the Pentagon has a number of hypersonic weapons programs in development and the U.S. understands the technology, China has “actually fielded hypersonic weapons,” Raytheon CEO Gregory Hayes said in an interview on Bloomberg Television’s “Balance of Power With David Westin.” “We are at least several years behind.”

The emerging, ultra-fast weapon systems have sparked concerns because of their potential to destabilize relations between the U.S., China and Russia. They may also become a front in the mounting competition between Beijing and Washington as the world’s two largest economies clash over trade, technology and humanitarian issues. Raytheon is developing a hypersonic cruise missile with the U.S. military.

Hypersonics capability is “the most destabilizing threat to the homeland,” Hayes said. “The time to react is very, very short.”

The CEO’s comments come after reports that China conducted two hypersonic weapons tests over the summer, including one of a so-called hypersonic glide vehicle. Launched from a missile or rocket, the craft separates and zips toward a target while maneuvering through the atmosphere, and Hayes said such weapons can reach speeds of 22,000 miles per hour.

“We have to have automated systems to defend the homeland, and we are focused on that,” he said in the interview.

Raytheon’s Missiles and Defense unit in September successfully test-fired a hypersonic cruise missile that can travel at speeds greater than Mach 5 as part of a development contract for the U.S. Air Force and the Defense Advanced Research Projects Agency, the Defense Department’s advanced technology development agency.

“We will have weapons to challenge the adversaries but most importantly I think our focus is how do we develop counter-hypersonics,” Hayes asid. “That’s where the challenge will be.”

Raytheon shares were down 2.5% to $88.99 at 2:38 p.m. in New York after the company reported third-quarter earnings.