The United States must accelerate the development of high-velocity rocket technology that is able to “defeat” ballistic missiles defense systems to keep up with the capabilities being honed by China and Russia, warned a top commander and key lawmakers.

During a Senate Armed Services Committee hearing last week, Gen. John Hyten, the head of U.S. Strategic Command (STRATCOM), suggested current ballistic missile defense systems employed by America are unable to stop such weapons, known as hypersonic, which refers to missiles that can fly more than five times the speed of sound.

To prevent a hypersonic missile strike, the U.S. would have to rely on nuclear deterrence, or the threat of a retaliatory U.S. strike, reports The Hill.

Gen. Hyten told lawmakers:

We don’t have any defense that could deny the employment of such a [hypersonic] weapon against us, so our response would be our deterrent force, which would be the triad and the nuclear capabilities that we have to respond to such a threat. … I believe we need to pursue improved sensor capabilities to be able to track, characterize and attribute the threats, wherever they come from. And, right now, we have a challenge with that, with our current on-orbit space architecture and the limited number of radars that we have around the world.

The Hill acknowledges that China and Russia are exceeding America’s capabilities in the development of hypersonic weapons.

While Russia claims, “it successfully tested a so-called hypersonic missile this month … China tested a similar system last year expected to enter service soon,” notes the news outlet.

Although Thomas Karako, the director of the Missile Defense Project at the Center for Strategic and International Studies, told The Hill the U.S. is “falling behind” China and Russia on hypersonic weapons, a group of 40 House Democratic lawmakers reportedly came out against devoting money to the development of new weapons.

Gen. Hyten noted that adversaries like Russia and China “are investing significant resources in hypersonic weapon research and development with the goal of deploying hypersonic strike weapons in the next few years.”

Meanwhile, the Pentagon “is pursuing hypersonic capabilities along several lines of effort, but we need to prioritize and accelerate development if we are to field our own capability in the near term.”

Echoing other Republican lawmakers as he advocated for increased investment in hypersonic military technology along with improving America’s missile defenses, Sen. James Inhofe (R-OK), a senior member of the Senate Armed Services Committee, told The Hill, “Right now, we’re helpless.”

There “appears to be no defense” against hypersonic weapons, the Oklahoma Republican emphasized.

Gen. Hyten described a hypersonic weapon to the Senate panel last week as a missile that starts out “like a ballistic missile, but then it depresses the trajectory and then flies more like a cruise missile or an airplane. So it goes up into the low reaches of space, and then turns immediately back down and then levels out and flies at a very high level of speed.”

“As our competitors continue to move fast in this area, we must retake the initiative and commit the necessary resources to develop and field hypersonic conventional weapons,” Gen. Hyten declared in written testimony.

Hyten acknowledged that the United States still needs to reach “the technical maturity required to field an effective hypersonic strike solution within the near future.”

The general explicitly noted that China’s military modernization efforts have expanded to developing hypersonic capabilities that can threaten the United States, telling senators: “China is swiftly developing and testing a hypersonic-glide vehicle capability, a technology used to defeat ballistic missile defenses.”

U.S. officials expect China’s hypersonic weapon capabilities to reach initial operating capability by around 2020, reports The Hill.

During his state of the nation address this month, Russian President Vladimir Putin touted the Kremlin’s development of several new weapons, including a hypersonic missile he alleged was “invincible” against U.S.-NATO missile defense systems.

“About a week later, Russia claimed it successfully tested a hypersonic,” notes The Hill, adding, “At the time of Putin’s announcement, the Pentagon said it was ‘not surprised’ by the report and assured the public that it is ‘fully prepared’ to respond to such a threat.”

However, Gen. Hyten conceded hypersonic weapons can “defeat” U.S. missile defense systems.