SEOUL — US and South Korean troops increased alert levels Wednesday as South Korea's foreign minister warned that North Korea could launch its medium-range Musudan missile ''any time from now.''
Although North Korea has tested many of its short-range Scud and medium-range Rodong missiles, it has never flight-tested the longer-range Musudan, which is believed to have a range of around 2,175 miles. A successful test of the missile would demonstrate the North's potential to hit not only South Korea but also all of Japan and targets as far away as the US military bases on the Pacific island of Guam.
''Based on intelligence we and the Americans have collected, it's highly likely that North Korea will launch a missile,'' Foreign Minister Yun Byung Se of South Korea told a parliamentary hearing Wednesday, adding that such a test would violate UN resolutions banning the country from testing ballistic missiles. ''Such a possibility could materialize at any time from now.''
US and South Korean troops raised their ''Watchcon'' level of vigilance, stepping up monitoring and intelligence-gathering activities, officials at the South Korean Defense Ministry said.
Adding to the concerns, North Korea often stages military provocations around important national anniversaries, and Monday is the birthday of North Korea's founder, Kim Il Sung, the grandfather of the current leader, Kim Jong Un.
Japan was also on guard for a potential North Korean missile launch, deploying PAC-3 missile interceptors in key locations around Tokyo as a precaution. The US military has moved two Navy missile-defense ships closer to the Korean Peninsula to monitor any North Korean missiles launchings and to intercept the missiles if they threaten the US bases or Washington's allies in the region.
South Korean military officials said that they had detected the movements of not only the Musudan but also Scud and Rodong missiles to the North's east coast, indicating that the North might fire those missiles together, as they had done before.
Despite warnings from their leaders of impending nuclear war, residents of Pyongyang gave no sense of panic, with people planting trees and dancing in the plazas ahead of the holiday, the Associated Press, which has a bureau in the North Korean capital, reported Wednesday.
The North Korean warnings also appeared to have little or no effect on the small Pyongyang community of foreign diplomats, who had been admonished by the host government last week that it could not guarantee their safety as of Wednesday and that they should consider evacuating.
A spokeswoman for Catherine Ashton, the top foreign policy official at the European Union, said in Brussels that despite North Korea's ''aggressive rhetoric, we judge that the situation on the ground does not justify evacuation or relocation.''
The spokeswoman, Maja Kocijancic, said this message had been delivered via the Swedish Embassy to North Korea's Foreign Ministry, along with a reminder that under the Vienna Convention on Diplomatic Relations, North Korea ''has a continuing obligation in all circumstances to protect diplomatic missions and EU citizens.''
Besides Sweden, the EU members with embassies in Pyongyang include Britain, Bulgaria, the Czech Republic, Germany, Poland, and Romania.
The military activity came as tensions continued to affect economic ties between the two Koreas. For a second consecutive day, North Korean workers did not turn up for work Wednesday at the industrial complex the two Koreas had run jointly in the North Korean city of Kaesong. About 110 South Koreans returned home Wednesday, reducing the number of South Koreans staying there to 297.
North Korea suspended operations at the factory park in response to ongoing joint US-South Korean military drills and UN sanctions imposed for its Feb. 12 nuclear test.
The money earned by North Korean workers at Kaesong has been a key source of badly needed foreign currency for the North Korean regime. Wednesday was a payday for North Korean workers, but with the North blocking anyone from the South from entering the industrial zone, South Korean factory owners had no way to pay their North Korean workers.
There were also signs that the tensions were starting to hurt tourism to the North. Officials in Dandong in northeastern China told tour operators to halt overland tourism into North Korea, local travel agents told Reuters.
Also Wednesday, South Korea officially blamed North Korea for launching a series of hacking attacks that paralyzed the computer networks of three broadcasters and three banks, as well as several government websites, in the South last month.