A North Korean launch of a missile on the birthday of its revered founder appears to have failed, US defence officials said.
The launch was on Friday's birthday anniversary of the late Kim Il Sung, the current leader's grandfather and the nation's founder.
North Korea has occasionally used such celebrations to stage nuclear or missile tests that outsiders consider provocations, and it would be an embarrassing failure for Pyongyang, if confirmed.
A senior US defence official said US Strategic Command systems had detected and tracked what officials assessed as a failed North Korean missile launch.
"We strongly condemn North Korea's missile test in violation of UN Security Council Resolutions, which explicitly prohibit North Korea's use of ballistic missile technology," the official said.
South Korea's Yonhap news agency said the failed launch was of a powerful new mid-range missile that could one day be capable of reaching far-off US military bases in Asia.
Seoul's defence ministry said it was not immediately known whether the launch was of a short-range or mid-range missile.
The launch comes as the two Koreas trade threats amid Pyongyang's anger over annual South Korean-US military drills that North Korea calls a rehearsal for an invasion.
The North has fired a series of missiles and artillery shells into the sea in an apparent protest against the drills.
A recent surge in belligerent threats and nuclear and missile activity in the North may also be linked to leader Kim Jong Un's preparations for a major ruling party meeting next month that analysts believe he will use to further solidify his autocratic rule.
The North's launch came amid speculation in the South that its rival was preparing to test a medium-range missile with a range of 2,180 miles - enough to reach US military bases in Japan and Guam.
North Korea has unnerved the international community this year with an escalating campaign of belligerence. This includes a nuclear test in January, its fourth, and a long-range rocket launch in February, as well as nuclear threats against the US and Seoul.
There is debate among analysts about the exact state of the North's nuclear capabilities.
Many believe Pyongyang has a handful of crude nuclear bombs - but each nuclear and missile test pushes them farther along in their goal of a nuclear-armed arsenal of long-range missiles.