X-51A Waverider. | EPA Arms race goes hypersonic The U.S. is competing with Russia and China to make weapons faster than ever before.

The United States, Russia and China are waging a secret arms race that could soon usher in a new generation of high-speed weapons never before seen in warfare.

In one test, a missile built by Boeing flew more than 230 miles in just four minutes. In another, a prototype designed by Lockheed Martin blasted off like a rocket and streaked back through the atmosphere at more than 20 times the speed of sound. China has reportedly tested its version over a lake in Inner Mongolia. And in February, Russia joined the fray when it tested a model that intelligence experts assert could be designed to carry a nuclear warhead.

Such hypersonic weapons, intended to attack targets many times faster than the speed of sound — before a defender could even react — have become the newest hope for military commanders seeking to gain an edge over potential adversaries. While most details and the level of funding remains classified, some predict they could be perfected within the next five years.

Critics both inside and outside of the military fear these futuristic missiles could be dangerously destabilizing, but Congress is pushing to accelerate development of these weapons. The missiles could render obsolete even the most advanced missiles defenses and provide a new means to deliver nuclear warheads, prompting some to call for an outright ban.

“We’re just doing it because maybe we can, and because others can too, and people are deluded that it represents some kind of major advance that we can exploit to keep the Chinese or Russian menace at bay,” said physicist Mark Gubrud, a professor in the Curriculum of Peace, War and Defense at the University of North Carolina.

“I think serious strategic thought leads to the conclusion that we would be much better off using our narrow lead to induce others to join us in a moratorium and banning these things,” he said.

Those who are are sounding the alarm, including some members of the military itself, will have to turn the tide of growing enthusiasm. As one senior Pentagon weapons scientist recently assured Congress, hypersonic weapons “will provide us an advantage in a contested environment in the future.” A top missile-builder, Raytheon, calls hypersonic weapons “the new frontier of the missile business.” And new legislation working its way through Congress, which seems firmly on board, urges the Pentagon to step up development, including seeking new ways to defend against hypersonic missiles.

The supposed difficulty of defeating a hypersonic attack is central to its appeal. For example, American commanders worried that an adversary could keep American warships or aircraft well away from contested areas like the idea of launching an attack from thousands of miles away.

“That’s really the future,” Steven Walker, deputy director of the Defense Advanced Research Projects Agency, told the Senate Appropriations Committee this spring.

“If you could combine that capability with any of our platforms, we will have a capability that will provide us an advantage in a contested environment in the future,” Walker said.

The Pentagon’s interest in advanced high-speed weapons goes back years, but one origin of the latest effort was the George W. Bush administration’s desire for “prompt global strike” — the ability to hit a target anywhere on the planet in about one hour with a non-nuclear weapon.

Officials discussed putting conventional warheads on ballistic missiles built to carry nuclear warheads, but any ballistic launch carried the risk that Russia or China might misinterpret it as a nuclear attack. A guided hypersonic weapon is thought to reduce the risk of a miscalculation, although Gubrud and other skeptics say it could be just as risky.

The Pentagon has already spent hundreds of millions of dollars on such tests and experiments, according to a report from the Congressional Research Service. Many of the details of hypersonic weapons developments remain secret. So far, U.S. military hypersonic tests are known to have included both successes and failures in a few Army and Air Force experiments.

China has acknowledged at least one hypersonic test flight, which took place last year, and the Pentagon’s annual report to Congress on Chinese military developments described its attempt to develop “several new classes and variants of offensive missiles.”

Russia, meanwhile, is said to have flown its hypersonic missile as recently as February, according to reports, the latest test in an effort about which there is little reliable information.

Defense contractors also see immense opportunity. Boeing and Lockheed both have built demonstrators as part of the Pentagon’s research programs. Raytheon is working on a missile that it says could skip off the atmosphere before plunging toward its target.

“There are multiple services — Army, Air Force, Navy — all very interested in the potentially transformative capabilities of hypersonic weapons,” Raytheon said in a statement. “Hypersonics represent the new frontier of the missile business.”

Congress also seems intent on pressing ahead with the technology more aggressively. Lawmakers have cited the Russian and Chinese tests — which experts assert are merely a response to the U.S. research.

“The committee is aware of the rapidly evolving threat from potential adversaries’ development of hypersonic weapons,” the House version of this year’s defense policy bill says. “The committee is also aware of several recent tests by the People’s Republic of China of hypersonic weapons, as well as other hypersonic weapon developments by the Russian Federation and the Republic of India. The committee believes this rapidly emerging capability could be a threat to national security and our operational forces.”

The House bill also directs the Pentagon to use the “residual technology” left over from its previous hypersonic tests to help develop ways to defend against what it calls the danger of new threats.

An added danger, warn skeptics, is the potential marriage of hypersonic missiles with nuclear weapons.

The U.S. is seeking conventional hypersonic weapons, not nuclear ones. But China and Russia are believed to be developing weapons that carry both types of warheads, likely designed to evade U.S. or other missile defense systems. One much-discussed Chinese system, the DF-21D, is built to launch from a rocket and then plunge down from space to attack U.S. aircraft carriers in the Pacific.

The skeptics warn that their use in war would almost certainly ratchet up the stakes of a conflict to dangerous levels at dangerous speeds.

“These things do create escalation risks that I don’t think have been adequately studied,” said physicist James Acton, co-director of the Nuclear Policy Program at the Carnegie Endowment, a Washington think tank. “It’s developing the technology without thinking, big picture, about the pros and cons.”

There are other influential voices that are also making the case for rethinking the current trajectory — including Air Force Lt. Col. Jeff Schreiner, a B-2 Spirit stealth bomber pilot.

“With nuclear technology the adage that ‘you can’t put the genie back in the bottle’ is widely used,” he wrote last fall. “What if we are standing at the threshold of a technology that we could keep in the bottle before it runs amok in the international system?

“There is a window for action open right now,” he added. “The U.S. should weigh the long-term strategic advantages of these weapons against the possible risks that they could destabilize the international system … We have the chance to lead the world out of an arms race instead of into one.”