The US Air Force deployed B-52 bombers to Qatar on Saturday to join the fight against Islamic State of Iraq and the Levant - the first time the aircraft have been based in the Middle East since the end of the Gulf War in 1991.

Washington's decision to deploy its powerful B-52 bombers to the Al Udeid Air Base came as the American military stepped up the fight in neighbouring Iraq and Syria against ISIL, also known as ISIS.

"The B-52 demonstrates our continued resolve to apply persistent pressure on Daesh and defend the region in any future contingency," said Air Force Lieutenant General Charles Brown, commander of US Air Forces Central Command, using the Arabic acronym for ISIL.

Lieutenant Colonel Chris Karns, spokesman for the Central Command, said he could not provide the exact number of B-52 bombers to be based at Al Udeid because of "operational security reasons".

Brown said the bombers would be able to deliver precision weapons and carry out a range of missions, including strategic attack, close-air support, air interdiction, and maritime operations.

Karns said the bombers would enable US forces to drop one or two munitions in an area, rather than massive indiscriminate bombing.

"Accuracy is critically important in this war," he said. "Carpet-bombing would not be effective for the operation we're in because Daesh doesn't mass as large groups. Often they blend into population centres. We always look to minimise civilian casualties."

The Central Command said it last flew the long-range bombers operationally in the region in May 2006 as part of the war in Afghanistan, and during a US-led military exercise in Jordan in May 2015.

 Afghan hospital attack: No criminal charges for US troops

Source: Reuters