South Korea's military said a missile launch by North Korea early Sunday from the port city of Sinpo "is presumed to have failed."
South Korea's Joint Chiefs of Staff did not provide details of the launch, and it was not immediately clear what type of missile was fired.
The launch came less than a day after a massive military parade in the North Korean capital that was widely viewed in world capitals as a show of force by the government of Kim Jong Un.
South Korea's official Yonhap News Agency said Seoul's national security chief would convene the National Security Council later Sunday to assess the situation.
There was no immediate comment from Washington, which is engaged in a sharp, multinational diplomatic offensive aimed at persuading North Korean leader Kim Jong Un to end his push to develop nuclear weaponry.
A short while after the launch, a statement from the U.S. Pacific Command said the missile blew up almost immediately and that its type was still being assessed.
The statement also reiterated Washington's full commitment "to working closely with our allies," particularly South Korea and Japan, to maintain security.
U.S. Vice President Mike Pence, en route to South Korea late Saturday (Washington time), was briefed on the failed launch and conferred with President Donald Trump, according to a statement from his office.
Earlier this week, as tensions worsened between Washington and Pyongyang, Trump ordered a U.S. naval strike group headed by the USS Carl Vinson aircraft carrier to the Korean Peninsula in show of force.
Pyongyang conducted two unauthorized nuclear test explosions last year and nearly two dozen rocket launches in a years-long push to expand its nuclear weapons and ballistic missile programs.
North Korean leader Kim declared in a speech on New Year's Day that his country's program to build intercontinental ballistic missiles had "reached its final stage."
Years of sanctions
Pyongyang has been under United Nations sanctions since 2006, along with an international arms embargo aimed at slowing its development of its banned nuclear and missile programs.
Since then, Washington and a vast majority of world governments have repeatedly demanded that the North denuclearize the Korean Peninsula. However, Western leaders have yet to devise a plan that would either compel the North to cooperate or create incentives for it to do so.
Trump has in recent weeks pressed China to persuade its North Korean ally to curb its nuclear ambitions, but results of those efforts are not yet clear.