Pentagon says in a report, China is expanding its nuclear force much faster than U.S. officials predicted just a year ago.

The United States is not as advanced in hypersonic technologies as Russia or China, US Vice Chief of Space Operations Gen. David Thompson said.

"We are not as advanced as the Chinese or the Russians in terms of hypersonic programs," Sputnik quoted Thompson as saying. He was speaking at the Halifax International Security Forum on Saturday.

Hypersonic missiles fly at least five times at the speed of sound but their ability to glide on the atmosphere while changing direction at such a high speed makes them virtually impossible -- with existing radars -- to track and destroy.

Currently, Russia is the only country possessing fully operational hypersonic missiles, Sputnik reported.

The Russian armed forces have the Kh-47M2 Kinzhal air-launched ballistic missiles, the Avangard hypersonic glide vehicles, and the 3M22 Zircon anti-ship hypersonic cruise missile is being tested.