The US and South Korea have said they have deployed a powerful B-52 bomber over the Korean peninsula in a show of force against North Korea following its nuclear test. The long-range strategic B-52 Stratofortress returned to its Guam base on the Pacific island after the fly-over.

When the bomber flew past the Osan air base in South Korea's Gyeonggi Province, it was flanked by South Korea's F-15 and US F-16 fighters. The bomber is capable of delivering nuclear weapons and its presence is bound to infuriate Pyongyang. The landing of the aircraft in the region will be seen as a direct threat by Pyongyang.

"This was a demonstration of the ironclad US commitment to our allies in South Korea, in Japan, and to the defence of the American homeland. North Korea's nuclear test is a blatant violation of its international obligations," said Admiral Harry B Harris Jr, commander of the US Pacific Command.

South Korea has been keen on the US deploying strategic weapons – including fighters and nuclear-powered submarines – ever since tensions escalated in the Korean peninsula when North Korea conducted its fourth nuclear test on 6 January. Pyongyang claimed it was a sophisticated hydrogen bomb detonation. Similar flights by B-52 bombers on earlier occasions had drawn a sharp response from the North.

Meanwhile, Seoul's defence ministry has ordered South Korean military forces to place missile operations in a state of readiness. Defence Minister Han Min-koo told the country's missile command during inspection: "If the enemy provokes, retaliate speedily and accurately without hesitation. Missile Command is a powerful force that gives confidence to South Korean people and fear to the enemy, as well as a core strike unit of the Kill Chain."