Seoul - The US flew four stealth fighter jets and two bombers over the Korean peninsula on Monday in a show of force after North Korea's latest nuclear and missile tests, a report said.Four F-35B stealth fighters and two B-1B bombers staged "mock bombing drills" over the peninsula on Monday morning, South Korea's Yonhap news agency said, citing an unidentified Seoul government source.If confirmed, they would be the first flights since the North conducted its sixth and most powerful nuclear test on September 3 and staged an intermediate-range missile test over Japan last Friday, sending regional tensions soaring. The US jets trained together with four South Korean F-15K jet fighters before returning to their bases in Japan and Guam, Yonhap quoted the source as saying.The previous such flights were on August 31. The US military could not immediately confirm the latest flights. The US is ramping up pressure on the North, with its ambassador to the UN Nikki Haley warning that Pyongyang would be "destroyed" if it refused to end its "reckless" weapons drive. Efforts to tame the increasingly belligerent North are set to dominate US President Donald Trump's address to the UN General Assembly and his meetings with South Korean and Japanese leaders this week. Tensions flared again when Kim Jong-Un's regime tested what it termed a hydrogen bomb many times more powerful than its previous device. The North also fired a ballistic missile over Japan and into the Pacific on Friday, responding to new UN sanctions over its atomic test with what appeared to be its longest-ever missile flight. Trump and South Korean President Moon Jae-In spoke by phone on Saturday and vowed to exert "stronger pressure" on the North, with Moon's office warning that further provocation would put it on a "path of collapse".Trump has also not ruled out a military option, which could leave millions of people in the South Korean capital - and 28 500 US soldiers stationed in the South - vulnerable to potential retaliatory attack. Trump's National Security Advisor HR McMaster said the US would "have to prepare all options" if sanctions prove insufficient to stop the North's weapons drive.