North Korea attempted to launch a missile on Sunday near Sinpo, on its east coast, but it is believed to have failed, South Korea's military said.
The attempted missile launch comes a day after North Korea held a military parade in its capital marking the birth anniversary of the state founder where what appeared to be new ballistic missiles were displayed.
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"The North attempted to launch an unidentified missile from near the Sinpo region this morning but it is suspected to have failed," the South's Office of the Joint Chiefs of Staff said in a statement.
There were no further details, and the office said it was analyzing the launch.
North Korea launched a ballistic missile from the same region earlier this month ahead of a summit meeting between the leaders of the United States and China, its key ally, to discuss the North's increasingly defiant arms program.
U.S. Pacific Command detected and tracked what it assessed to be a North Korean ballistic missile launch at 11:21 a.m. GMT on Saturday, said U.S. Navy Commander Dave Benham, a spokesman for U.S. Pacific Command.
"The missile blew up almost immediately," Benham said. "The type of missile is still being assessed."
Pyongyang, Washington tensions escalate
Tension had escalated sharply in the region amid concerns that the reclusive North Korea may soon conduct a sixth nuclear test or a ballistic missile test launch timed with the April 15 anniversary it calls the "Day of the Sun."
The White House has said U.S. President Donald Trump has put North Korea "on notice" while the possibility of U.S. military action against Pyongyang has gained traction following U.S. strikes against Syria on April 7.
Trump has ordered a navy strike group flagshipped by a nuclear-powered aircraft carrier to head to the region as a show of force as his officials assess tougher economic sanctions as well as military options against North Korea.
North Korea has in turn warned of a nuclear strike against the United States if provoked.
U.S. Vice-President Mike Pence, as part of a 10-day trip to Asia, arrives in South Korea on Sunday in what his aides said was a sign of the U.S. commitment to its ally in the face of rising tensions over the North's weapons programs.
Pence had been briefed on the failed launch en route to Seoul and had been in touch with Trump, the White House said.
U.S. Defence Secretary Jim Mattis said in a statement on Saturday that Trump and his military team are aware of the launch attempt.
North Korea 'threatens the whole world'
South Korea, which hosts 28,500 U.S. troops to help counter the threats from the North, warned of punitive action if the launch led to further provocations such as a nuclear test or a long-range missile launch.
"North Korea showing a variety of offensive missiles at yesterday's military parade and daring to fire a ballistic missile today is a show of force that threatens the whole world," South Korea's Foreign Ministry said in a statement.
The South's National Security Council said it would respond strongly to any further provocation.