PYONGYANG, North Korea -- As the world braced for a provocative missile launch by North Korea, with newscasts worldwide playing up tensions on the Korean Peninsula, the centre of the storm was strangely calm.

The focus in Pyongyang on Wednesday was less on preparing for war and more on beautifying the capital ahead of the nation's biggest holiday: the April 15 birthday of the nation's founder, Kim Il Sung. Soldiers put down their rifles to blanket the barren ground with sod and students picked up shovels to help plant trees.

But the impoverished, tightly controlled nation that has historically used major holidays to draw the world's attention by showing off its military power could well mark the occasion by testing a missile designed to strike U.S. military installations in Japan and Guam.

South Korea's foreign minister said the prospect of a medium-range missile launch is "considerably high."

North Korean officials have not announced plans to launch a missile in defiance of U.N. Security Council resolutions barring Pyongyang from nuclear and missile activity.

But they have told foreign diplomats in Pyongyang that they will not be able to guarantee their safety starting Wednesday and urged tourists in South Korea to take cover, warning that a nuclear war is imminent. Most diplomats and foreign residents in both capitals appeared to be staying put.

The European Union said there was no need for member states to evacuate or relocate their diplomatic missions, but it called on North Korea to "refrain from further provocative declarations or action."

The threats are largely seen as rhetoric and an attempt by North Korea to scare foreigners into pressing their governments to pressure Washington and Seoul to change their policies toward Pyongyang, as well as to boost the military credentials of its young leader, Kim Jong Un. North Korea does not have diplomatic relations with the U.S. and South Korea, its foes during the Korean War of the 1950s, and has pushed for a peace treaty to replace a 60-year-old armistice.

On the streets of Pyongyang, there was no sense of panic.

Downtown, schoolchildren marched toward statues of the two late leaders, Kim Il Sung and Kim Jong Il, dragging brooms to sweep the hilltop plaza where they tower over Pyongyang. Women with coats thrown over traditional dresses rushed through the spring chill after leaving a rehearsal for a dance planned for Kim Il Sung's birthday celebrations.

At the base of Mansu Hill, a group of young people held a small rally to pledge their loyalty to Kim Jong Un and to sing the Kim ode, "We Will Defend the Marshal With Our Lives."

Kim Un Chol, the 40-year-old head of a political unit at Pyongyang's tobacco factory, said he had been discharged from the military but was willing to re-enlist if war breaks out. He said North Koreans were resolute.

"The people of Pyongyang are confident. They know we can win any war," he told The Associated Press. "We now have nuclear weapons. So you won't see any worry on people's faces, even if the situation is tense."

Kim Jong Il elevated the military's role during his 17-year rule under a policy of "military first," and the government devotes a significant chunk of its annual budget to defence. Human rights groups say the massive spending on the military and on development of missile and nuclear technology comes at the expense of most of its 24 million people. Two-thirds face chronic food shortages, according to the World Food Program.

North Koreans are taught from childhood to hate the U.S. and to gird against an invasion by "imperialists" intent on taking over the entire Korean Peninsula.

Guns and tanks are popular toys for children in the highly militarized society, and young North Koreans learn to fire guns when they are teenagers, residents say. As young adults, they attend camps to learn military techniques.

But there was no sign North Koreans were brushing up on their skills Wednesday. Pyongyang sporadically holds civil air raid drills in which citizens practice blacking out their windows and seeking shelter. But no such drills have been held in recent months, residents said.

Last year, the days surrounding the centennial of the birth of Kim Il Sung, grandfather of the current ruler, were marked by parades of tanks, missiles and goose-stepping soldiers, as well as the failed launch of a satellite-carrying rocket widely believed by the U.S. and its allies to be a test of ballistic missile technology.

A subsequent test in December was successful, and that was followed by the country's third underground nuclear test on Feb. 12, possibly taking the regime closer to mastering the technology for mounting an atomic weapon on a missile.

Last week, Kim Jong Un enshrined the pursuit of nuclear weapons -- which the North characterizes as a defence against the U.S. -- as a national goal, along with improving the economy. North Korea also declared it would restart a mothballed nuclear complex.

The resulting U.N. sanctions and this spring's annual U.S.-South Korean military drills, which Pyongyang sees as a rehearsal for invasion, have been met with a string of threats from the North. Washington denies it has any plans to invade, and calls the exercises routine defensive drills.

Adm. Samuel Locklear, commander of U.S. Pacific Command, told the Senate Armed Services Committee in Washington on Tuesday that North Korea's persistent nuclear and missile programs and threats have created "an environment marked by the potential for miscalculation."

He said the U.S. military and its allies would be ready if North Korea tries to strike.

Citing the tensions, North Korea on Monday pulled more than 50,000 workers from the Kaesong industrial park, which combines South Korean technology and know-how with cheap North Korean labour. It was the first time that production was stopped at the decade-old factory park, the only remaining symbol of economic co-operation between the Koreas.

In Seoul, South Korean Foreign Minister Yun Byung-se told lawmakers the North Korean missile is expected to have a range of about 3,500 kilometres (2,180 miles).

A Defence Ministry official told the AP preparations appeared to be complete, and that the launch could take place at any time. He spoke on condition of anonymity, saying he wasn't authorized to speak to the media.

The missile, dubbed "Musudan" by foreign experts after the name of the northeastern village where North Korea has a launchpad, is mainly designed to reach the U.S. territory of Guam, though it can also place U.S. military installations in Japan in its striking range, experts said.

As a precaution, Japan has deployed PAC-3 missile interceptors in key locations around Tokyo while the South Korean and U.S. militaries have raised their level of surveillance.

The International Civil Aviation Organization said Wednesday it has received no notice of a missile launch from North Korea, but that it is not mandatory for Pyongyang to inform the organization. North Korea has worked with ICAO in the past to notify air traffic authorities in other countries of its plans to launch rockets.

In London, Russian Foreign Minister Sergey Lavrov urged a calm response from all.

"You should not scare anyone with military manoeuvrs," he said, speaking in Russian, before meeting with U.S. Secretary of State John Kerry. "And then there's a chance everything can calm down."

One historian, James Person, noted that it isn't the first time North Korea has warned that a war was imminent.

He said that in 1968, following North Korea's seizure of an American ship, the USS Pueblo, Pyongyang persistently advised foreign diplomats to prepare for a U.S. counterattack. Cables from the Romanian mission in Pyongyang showed embassies were instructed to build anti-air bunkers "to protect foreigners against air attacks," he said.

The cables were obtained and posted online by the Wilson Center's North Korea International Documentation Project.

Person called it one of North Korea's first forays into what he calls "military adventurism."

"In 1968, there was some concern there would be an attack, but (the North Koreans) certainly were building it up to be more than it was in hopes of getting more assistance from their allies at the time," Person said by phone from Alexandria, Virginia.

"I think much of it was hot air then. Today, I think again, it's more hot air," he said. "The idea is to scare people into pressuring the United States to return to negotiations with North Korea. That's the bottom line."