An experimental hypersonic weapon which could one day be capable of striking any target around the world within an hour was destroyed seconds after launching from a US military test-bed in Alaska.

The weapon, which is being developed by the US military, self-destructed four seconds after its launch from a test range in Alaska early on Monday after controllers detected a problem with the aircraft, the Pentagon said.

The craft was destroyed to ensure public safety, and no one was injured in the incident, which occurred shortly after 4 a.m. EDT (0800 GMT) on Monday at the Kodiak Launch Complex in Alaska, said Maureen Schumann, a spokeswoman for the U.S. Defense Department.

"We had to terminate. That's correct,” Schumann said. “The weapon exploded during takeoff and fell back down in the range complex,” she said, adding that the test craft was destroyed in the first four seconds of its launch.

“I don't know the exact altitude, but it was not very far,” she said.

The weapon was developed by Sandia National Laboratory and the US Army as part of the military's "Conventional Prompt Global Strike" technology development program.

The weapon is intended to give the US president “the ability to promptly engage targets at a strategic range without using nuclear weapons” according to an declassified environmental impact assessment released in June 2011.

Scott Wight, a local photographer, observed the launch from about miles away. He described the explosion seconds after the rocket appeared to veer out of control as “a scary sight to see” according to the local KMXT radio station.

When perfected, designers hope the weapon – a “hypersonic glide body” released from the nose-cone of a rocket that carries it to the edge of the earth’s atmosphere - will reach speed of Mach 5, or 3,600 miles per hour.

Ms Schumann said the craft, known as the “Advanced Hypersonic Weapon”, was one of several platforms being tested as part of the Prompt Global Strike program.

The craft had successfully flown the 2,500 miles from Hawaii to the Kwajalein Atoll in the Marshall Islands during a previous test in November 2011, she said.

The weapon, described by the Army as a first-of-its-kind glide vehicle, was supposed to fly from Alaska to the Kwajalein Atoll during Monday's test.

Schumann said that, in addition to the previous successful flight test, the hypersonic weapon had "gone through a series of ground testing and modeling and simulation."

She said she wouldn't characterise Monday's terminated flight as a significant setback for the prompt global strike program.

“This was one concept that we were looking at in a range of possible CPGS (Conventional Prompt Global Strike) concepts,” she added.

“The whole CPGS program is event-driven, not time- or schedule-driven. So we learn, we keep learning from a variety of ground testing and modeling and simulation and other tests done on the range of concepts under CPGS.”

Schumann said officials from the program, the U.S. Army, Navy and Missile Defense Agency were conducting an extensive investigation to determine the cause of the accident.

The investigation will inform future tests for the weapon and other prompt global strike vehicles, she said.

Reuters