The US Air Force on Saturday deployed Cold War-era B-52 bombers to bolster the fight against ISIS in Syria and Iraq, stepping up efforts to defeat the extremists.
The B-52 Stratofortress aircraft, which arrived in Qatar, were based in Saudi Arabia and last flown operationally in May 2006 as part of the war in Afghanistan, air force officials said.
"The B-52 will provide the coalition continued precision and deliver desired airpower effects," said Lieutenant General Charles Brown, commander of US Air Forces Central Command.
The long-range planes will provide "flexibility and endurance" in the US-led coalition campaign against the jihadists, he added.
"The B-52 demonstrates our continued resolve to apply persistent pressure on (ISIS) and defend the region in any future contingency," Brown said.
The B-52, the first US long-range heavy bomber, was developed to carry nuclear weapons and has been adapted over the years. It has been used in missions in the Vietnam War, the 1991 Gulf War and in Afghanistan.
It was not immediately clear how many of the bombers had been deployed.
AFP contributed to this report