The U.S. Air Force is moving forward with plans to develop hypersonic cruise missiles.
The service has teamed with the Defense Advanced Research Projects Agency, or DARPA -- the Pentagon's research arm -- to fund development of the technology as part of the Hypersonic Air-breathing Weapon Concept program, or HAWC.
The agency in recent weeks awarded Raytheon Co., the world's largest missile maker, and Lockheed Martin Corp., the world's largest defense contractor, with contracts valued at roughly $170 million a piece to help develop the air-launched hypersonic weapons.
Weapons capable of traveling at hypersonic speeds of at least Mach 5, or five times the speed of sound, could operate farther away from targets and with faster response times, according to DARPA's website on the project. At such speeds -- 3,400 miles per hour -- a missile could travel from Washington, D.C., to Atlanta in just several minutes.
"These demonstrations seek to open the door to new, responsive long-range strike capabilities against time-critical or heavily defended targets," the DARPA website states.
Lockheed earlier this year touted a "breakthrough" in hypersonic technology and has floated the idea of developing a hypersonic spy plane for the U.S. military.
The Air Force wants to build on its research from previous efforts. In 2013, the service conducted its fourth and longest flight of the so-called X-51 WaveRider. After separating from a rocket launched beneath the wing of a B-52 bomber, the hypersonic vehicle built by Boeing Co. climbed to 60,000 feet, accelerated to Mach 5.1 and flew for about three and a half minutes before running out of fuel and plunging into the Pacific Ocean.
The WaveRider program, which had a couple of failed tests, came several years after a similar NASA effort called the X-43, which in 2004 shattered speed records when it flew at nearly Mach 9.7, or about 6,600 miles per hour, for 10 seconds. But the engine couldn't withstand the temperatures involved.