South Korea has raised its military alert status, a senior military official has said, as tensions remain high on the Korean peninsula.
The Combined Forces Command in Seoul has raised its "Watchcon 3" status, a normal defense condition, by one level in order to step up monitoring, South Korea's Yonhap news agency reported on Wednesday.
The senior Defense Ministry official also said that North Korea has completed preparations for a missile test that could come "any day".
The official, who spoke on condition of anonymity, said the North's military is capable of conducting multiple missile launches involving Scud and medium-range Rodong missiles, as well as a missile transported to the east coast recently.
The warning came as Pyongyang prepared to mark the April 15 birthday of its founder Kim Il-sung.
The date is historically a time when it seeks to draw the world's attention with dramatic displays of military power.
UN 'concerned'
Admiral Samuel Locklear, the commander of US forces in the Pacific region, said the US military also believed the North had moved an unspecified number of Musudan missiles to its east coast.
An Obama administration official, speaking on condition of anonymity, told the Reuters news agency "our working assumption is that there are two missiles that they may be prepared to launch".
Ban Ki-moon, UN secretary general, who once served as South Korean foreign minister, said he is "deeply concerned and troubled" at the level of tension in the peninsula.
"If any small incident caused by miscalculation or misjudgment, it may create an uncontrollable situation," Ban said.
Yun Byung-se, the South Korean foreign minister, told a parliamentary hearing in Seoul that he was working through diplomatic channels in an attempt to rein in Pyongyang.
"Through close coordination with China and Russia, the Korean government has been continuing to make efforts to persuade North Korea to change its attitude," Yun said.
China is North Korea's only major ally, although it backed recent United Nations resolutions against Pyongyang, and Moscow was a supporter of North Korea as the Soviet Union.
Unknown quantity
Pyongyang has frequently tested short-range Scud missiles, but the longer-range Musudan and Nodong missiles are an unknown quantity.
The Musudan missiles are reckoned to have a range of roughly 3,000-3,500km.
The North has earlier said it would target American bases in the Pacific, although it is not known whether the untested missiles have the range to do so.
"If the missile was in defense of the homeland, I would certainly recommend that action [of intercepting it]. And if it was defense of our allies, I would recommend that action," Locklear told a US Senate hearing in Washington.
Pyongyang has turned up its rhetoric in recent weeks after the United Nations Security Council imposed sanctions for the impoverished state's third nuclear weapons test in February.
It has threatened a nuclear strike on the United States - something it does not have the capacity to carry out - and "war" with the South Korea.
Leaving Kaesong
n a separate development, a group of South Korean workers left the joint industrial zone of Kaesong ahead of a deadline issued by North Korea to shut down the border.
Al Jazeera's Marga Ortigas, reporting from the border town of Paju, said a convoy of cars carrying the workers had crossed from the North on Wednesday morning.
She added that a total of 79 workers were expected to leave by the deadline, which was set to expire later on Wednesday.
Another 400 workers and business owners are still in the complex, and are expected to stay beyond the deadline.
The North has been threatening the United States and its "puppet" South Korea on an almost a daily basis in recent weeks, although the threats appear to be aimed partly at boosting internal support for young leader Kim Jong-un.
Analysts say the current tensions will likely last until the end of April, when joint US-South Korean military drills end.
PHOTO CAPTION
A South Korean military truck transporting soldiers drives past a soldier standing guard at a checkpoint on the Grand Unification Bridge, which leads to the demilitarized zone separating North Korea from South Korea, in Paju, north of Seoul April 10, 2013.
Al-Jazeera