Seoul – A North Korean missile launch likely failed on Tuesday, according to South Korea's military, the latest in a string of high-profile failures that somewhat tempers recent worries that Pyongyang was pushing quickly toward its goal of a nuclear-tipped missile that can reach America's mainland.South Korea's Yonhap news agency reported that the missile was a powerful mid-range Musudan. If true, that would make it the fourth failed attempt by the North to conduct a successful test launch of the new missile, which could potentially reach far-away US military bases in Asia and the Pacific.Yonhap, citing an unidentified government source, said the missile exploded at a mobile launch pad as soon as a launch button was pressed. The report, if confirmed, suggests the missile may have even failed to lift off. Yonhap did not say how its source obtained the information.Seoul defense officials said they could not immediately confirm the report.The South's Joint Chiefs of Staff said in statement that the North attempted to launch an unidentified missile early in the morning from the eastern coastal town of Wonsan, but that it likely failed. JCS officials said later on Tuesday they were analysing what happened but released no other details.UnsuccessfulDespite recent failures, there have been growing worries about North Korea's nuclear and missile activities this year, which includes a nuclear test in January and a long-range rocket launch in February that outsiders saw as a test of banned long-range missile technology.The most recent launch follows Seoul's rejection of recent Pyongyang overtures to talk, part of what some analysts see as an attempt by the North to win concessions from its rivals.In April, North Korea attempted unsuccessfully to launch three suspected powerful intermediate-range Musudan missiles. All the missiles exploded in mid-air or crashed, according to South Korean defense officials.South Korean officials believe the missile launches follow an order from the country's leader Kim Jong Un in March to conduct tests of a nuclear warhead and ballistic missiles capable of carrying such warheads. That order was thought to be part of Pyongyang's reaction to annual South Korea-US military drills that it sees as an invasion rehearsal.Musudan missiles have a potential range of about 3 500km, which would put US military bases in Guam within their striking distance. South Korea believes the North does not have a functional long-range missile capable of hitting the US mainland, but the North is working on that technology.Before April's suspected launches, North Korea had never flight-tested a Musudan missile, although one was displayed during a military parade in 2010 in Pyongyang.