The United States would not be surprised if North Korea were to conduct a new missile test, White House spokesman Jay Carney has told reporters.
Asked about indications that North Korea might be preparing to launch a test missile amid rising tensions in the region, Mr Carney said White House officials had seen the reports.
"We would not be surprised to see them take such an action," Mr Carney said. "We have seen them launch missiles in the past."
His comments come after North Korea placed two of its intermediate range missiles on mobile launchers and hid them on the east coast of the country in a move that could threaten Japan or US Pacific bases, South Korean media reported today.
The report could not be confirmed. But any such movement may be intended to demonstrate that the North, angry about joint US-South Korean military exercises and the imposition of UN sanctions, is prepared to demonstrate its ability to mount an attack.
The UN said today that its staff are continuing to work in North Korea while Secretary-General Ban Ki-moon studies a message from North Korea saying the world body should consider evacuating UN personnel from the country.
UN spokesman Martin Nesirky said a UN representative joined diplomats at a meeting in Pyongyang this afternoon where the North’s foreign ministry delivered the message.
“The Secretary-General is studying the message and the United Nations will respond as appropriate,” Mr Nesirky said.
He said UN staff “remain engaged in their humanitarian and developmental work throughout the country”.
The has 36 international staff and 21 national staff working for seven UN agencies and programmes, plus family members.
Mr Nesirky reiterated Mr Ban’s concern at escalating tensions spurred by North Korea’s recent nuclear threats.
Officials warned
British officials in North Korea have been warned that the authorities there would be unable to guarantee their safety in the event of conflict.
It is understood the British Foreign Office has no intention of evacuating the mission in the capital Pyongyang despite the North Korean regime saying it could not protect embassies and international missions if war broke out after April 10th.
A Foreign Office spokeswoman said: “The British Embassy in Pyongyang received a communication from the North Korean government this morning saying that the North Korean government would be unable to guarantee the safety of embassies and international organisations in the country in the event of conflict from April 10th.”
The North has said nuclear conflict could break out at any time on the Korean peninsula in a month-long war of words that has prompted the United States to move military assets into the region. The tension with North Korea has roiled South Korean financial markets and senior finance officials in Seoul warned they could have a long-term impact on markets.
In North Korea itself, there was no intensification of the strident rhetoric about impending war as the country marked a national holiday. And some analysts said the tone of recent statements, however bitter, was most probably aimed at securing concessions and was unlikely to lead to armed conflict.
South Korea's Yonhap news agency, quoting a senior military official said: "Early this week, the North moved two Musudan missiles on the train and placed them on mobile launchers."
South Korea's defence ministry declined to comment. Speculation centred on two kinds of missiles neither of which is known to have been tested.
The Musudan missile is estimated by South Korea's defence ministry to have a range of up to 3,000 km (1,865 miles) and the KN-08, believed to be an inter-continental ballistic missile, is untested.
In Seoul, officials from economic ministries, the central bank and regulatory agencies held emergency talks and promised swift and strong action should the markets lose stability. News of the talks and the central bank involvement boosted investors' expectations of an interest rate cut next week.
South Korean shares slid, with foreign investors selling their biggest daily amount in nearly 20 months, hurt after aggressive easing from the Bank of Japan sent the yen reeling, as well as by the tension over North Korea.
"In the past, (markets) recovered quickly from the impact from any North Korea-related event, but recent threats from North Korea are stronger and the impact may therefore not disappear quickly," vice finance minister Choo Kyung-ho told a meeting.
North Korea threatened to strike US military bases, including those on the American mainland, and to shut down a joint industrial complex with the South while denying entry to the complex by South Korean workers this week.
The South's new unification minister said the government was willing to pull out workers from the Kaesong industrial complex if it became dangerous, though he said the situation was not that serious for the moment.
The threats from North Korea's 30-year-old leader Kim Jong-un, though not unusual from the reclusive state, have followed the imposition of new UN sanctions in response to North Korea's third nuclear test in February. Reaction to the threats in markets has until now been muted.
The increasingly tense standoff with North Korea could not happen at a worse time for the government of the South's new president, Park Geun-hye, whose first steps in office included a sharp cut in growth forecasts.
Mrs Park, in office for just over a month, has ordered her cabinet to draw up what is likely to be a large supplementary budget to lower budget revenue projections and add new spending plans aimed at jump-starting faltering domestic demand.
"The market usually doesn't get jittery over North Korea threats. But this time is different, because they look willing to sacrifice Kaesong, which has never happened before," said Park Hyung-joon, macroeconomics team leader at Meritz Securities.
Some US analysts expressed a degree of alarm over the intensification of the threats.
"The rhetoric is off the charts," said Victor Cha, former director for Asian affairs at the White House National Security Council and now senior adviser at the Centre for Strategic Studies in Washington.
"We don't understand this new guy at all. And if the North Koreans move to provoke the South, the South is going to retaliate in a way we haven't seen before."
Other analysts said a degeneration into conflict was unlikely.
"We do not believe that North Korea intends to attack South Korea, pre-emptively or otherwise, in the current cycle of threat projection," the US-based Nautilus think-tank said in a study published yesterday.
"Rather, these statements are opportunistic, and express its authentic strategy which is extortionate. The North's nuclear forces are intended to compel their adversaries to change their policies towards (North Korea), not to deter unprovoked external attack-except when such an attack might actually be in motion."