South Korea and the US have said the latest missile launch by North Korea ended in a failure after the projectile reportedly exploded soon after lift-off.
The South Korean joint chiefs of staff said the military believes the North unsuccessfully attempted to fire a mid-range Musudan missile.
The failed launch was said to have taken place near an airport in the North's North Pyongan province.
South Korea strongly condemns the launch because it violates UN Security Council resolutions which ban any ballistic activities by North Korea.
The US military said the missile did not pose a threat to North America.
Pentagon spokesman Cmdr Gary Ross said: "We strongly condemn this and North Korea's other recent missile tests, which violate UN Security Council Resolutions explicitly prohibiting North Korea's launches using ballistic missile technology."
Cmdr Ross added: "Our commitment to the defence of our allies, including the Republic of Korea and Japan, in the face of these threats, is ironclad.
"We remain prepared to defend ourselves and our allies from any attack or provocation."
Japan has expressed concern over the launches, with defence minister Tomomi Inada saying that she wants to work in cooperation with the US and South Korea to assure her country's security.
North Korea has claimed technical breakthroughs in its goal of developing a long-range nuclear missile capable of reaching the continental United States. South Korean defence officials insist the North does not yet have such a weapon.
It is the latest in a series of moves by North Korea aimed apparently at displaying a show of force. As recently as last month, it fired three ballistic missiles off its east coast, timed to gain the attention of world leaders including US president Barack Obama who were visiting the region for a series of summits.
The UN Security Council subsequently condemned those North Korean launches and threatened "further significant measures" if it refuses to stop its nuclear and missile tests.
North Korea also conducted its fifth nuclear test last month and in all has launched more than 20 ballistic missiles this year, part of its programme aimed at improving the delivery system for nuclear weapons.
Earlier this year, North Korea successfully launched a Musudan missile in June after several failed attempts.
Musudan has a range of 2,180 miles - enough to reach U.S. military instalments in Japan and Guam.
Mr Obama has vowed to work with the United Nations to tighten sanctions against North Korea, but has also said that the US is still open to dialogue if the government changes course.
The US strategy has largely centred on trying to get China, North Korea's traditional ally, to use its influence to persuade the North to change course.
North Korea is continuing with missile test launches even as the UN Security Council is deliberating a further tightening of sanctions after the September nuclear test.
Previously in August, Japanese and South Korean officials said a medium-range ballistic missile flew about 620 miles and landed near Japan's territorial waters.