A top U.S. defense official said rival countries are developing hypersonic weapons that are capable of breaking through its missile defense system. "They are quite capable," U.S. Undersecretary of Defense for Research and Engineering Michael D. Griffin said during a discussion at the Hudson Institute in Washington Tuesday, apparently referring to Russia, China and Iran. "The advantage offered by a hypersonic offense is that it overflies air defenses as we understand them today, and it underflies our missile defenses. It goes into the gap between air defense and missile defense." Griffin said that hypersonic threats move so fast they're almost too fast to stop. A hypersonic weapon moving at five times the speed of sound can travel across the Pacific Ocean in less than two hours. "By the time we can see it on defensive radar systems, it's nearly too late to close the kill chain," he said. "It would be difficult to close that kill chain for one threat. But in a raid scenario, you just can't get there from here, ... so we have to see them coming from further out." Griffin said that detecting the threat from hypersonics in enough time to neutralize will require new detection systems in low Earth orbit. "We need a proliferated layer of sensors, because we can't see these things from a few spacecraft in geostationary orbit." Griffin told the audience that the Missile Defense Agency is developing a Hypersonic and Ballistic Tracking Space Sensor. But at the same time, he admitted that the U.S. Defense Department does not have a "communications layer", which is central to hypersonic defense. Griffin is the Pentagon's Chief Technology Officer, and is responsible for the research, development, and prototyping activities across the DoD. He oversees the activities of various Defense wings that are focused on developing advanced technology and capability for the U.S. military. With speeds surpassing Mach 5 and the ability to maneuver mid-flight, hypersonic weapons challenge the world's missile defense balance of power, which reportedly threatens the United States' current defenses. Defense Intelligence Agency Director Robert Ashley had said in his "Worldwide Threat Assessment" last year that Russia, China and Iran were developing increasingly sophisticated ballistic missile warheads and hypersonic glide vehicles in an attempt to counter the United States' ballistic missile defense systems. Currently there is no industrial base equipped to manufacture hypersonic weapons, and the U.S. military is said to be a few years behind its rivals in launching them. Griffin is not the first Pentagon official to admit the dominance of Russia and China in hypersonic weapons technology.