A recent United States Air Force scramjet test has hinted at a future where hypersonic vehicles streak through the sky at many times the speed of sound around the world, and perhaps even open up access to space.

The mission: Attack anywhere in the world in less than an hour. But is the Pentagon's bold program a critical new weapon for hitting elusive targets, or a good way to set off a nuclear war?

The Pentagon is spending billions of dollars on new forms of space warfare to counter the growing risk of missile attack from rogue states and the "satellite killer" capabilities of China.

China is starting to ramp up its scramjet propulsion work -- an initiative that will benefit high-speed missile programs. Over the next several decades, the scramjet work could eventually provide China with a tactical hypersonic global-strike capability beyond the country's strategic ballistic missile force. The U.S. has similar goals for its own growing scramjet program.

The Pentagon is working to develop a suborbital space capsule within the next five years that would be launched from the United States and could deliver conventional weapons anywhere in the world within two hours, defense officials said.

NASA's X-43A scramjet programme successfully smashed its own world speed record for aircraft by flying at nearly 10 times the speed of sound. While future funding for NASA research on hypersonic flight is uncertain, the test demonstrates the potential of hypersonic flight for other military applications.

The author looks at the military motivations behind the development of the X-34 hypersonic aircraft and warns that the test could herald a new era of warfare and a new space race between the U.S. and Russia.

The Pentagon is planning a new, more lethal, remotely operated aircraft that could bomb targets anywhere on Earth within a scant two hours of taking off from the United States.

The US military has begun development of an ultra-high speed weapons system that would enable targets virtually anywhere on Earth to be hit within two hours of launch from the continental US.

The author looks at several space weapons systems currently under consideration by the U.S. including kinetic-energy weapons, hypersonic planes, and space lasers.