U.S. Defense Secretary Robert Gates has stated that President Barack Obama approved the use of armed, unmanned Predator drone aircraft to assist the coalition military campaign in Libya.

Speaking to a news conference at the Pentagon, Marine General James Cartwright (who appeared next to Gates) explained that the Predators permit low-level precision attacks on Libyan government and military targets.

Cartwright also told reporters that precision attacks on Gaddafi's ground forces have become increasingly difficult for traditional aircraft as the battle lines in some cities have become harder to detect.

“What they will bring that is unique to the conflict is their ability to get down lower, therefore to be able to get better visibility on ... targets now that have started to dig themselves in into defensive positions,' Cartwright said.

Two Predator drones will be operational for periods of 24 hours, Cartwright added.

Previously, Predators has been used in Libya, but they were unarmed and used only to gather intelligence.

However, Gates cautioned that this decision does not necessarily signal as escalation of US involvement in Libya.

“This is a very limited additional role on our part but it does provide some additional capabilities to NATO,” Gates said.

Predators have been in use along the Pakistan-Afghanistan border for several years and have been used to target Taliban and Al-Qaeda forces there.