New York, Dec 21 (IANS): The US Department of Defense is testing a bullet that could change direction in mid-air.

The Extreme Accuracy Tasked Ordnance (EXACTO), currently being tested by the Defense Advanced Research Projects Agency (DARPA), is a .50 calibre round that can change direction as it flies towards it's target.

The details of how it will work are completely secret, Popular Science reported.

It is designed specifically for use by snipers, for whom slight improvements such as these could make the difference between life or death.

"The system combines a manoeuvrable bullet and a real-time guidance system to track and deliver the projectile to the target, allowing the bullet to change path during flight to compensate for any unexpected factors that may drive it off course," said the description on the DARPA website.

The EXACTO technology is now being tested in live firing situations to enhance and improve performance.