As the world watches to see what North Korea's next move will be in a high-stakes game of brinksmanship with the United States, residents of its capital aren't hunkering down in bunkers and preparing for the worst. Instead, they are out on the streets en masse getting ready for the birthday of national founder Kim Il Sung — the biggest holiday of the year.

The festivities leading up to Kim's birthday come amid fears that North Korea may be planning to test launch a new missile in retaliation for what it claims are provocative war games by U.S. and South Korean troops just across the Korean border. Even at such a seemingly innocuous setting as a flower show in Kim's honor, North Korea's warning that it is prepared to strike back if pushed too far is on prominent display.

This year's exhibition of "Kimilsungia" flowers — which North Koreans claim their scientists have bred into the most beautiful orchids in the world — is built around mockups of red-tipped missiles, slogans hailing the military and reminders of the threats that North Koreans feel are all around them.

"It is because we have a nuclear deterrent like nuclear weapons that we are able to live our normal lives and have a beautiful flower exhibition like this," said Kim Sung Sim, a Pyongyang greenhouse worker who contributed to the display, which opened Friday.

The escalation of tensions comes as North Korea is also celebrating a slew of anniversaries for its young leader, Kim Jong Un, who took power in December 2011 following the death of his father, longtime leader Kim Jong Il. He was named head of the Workers' Party a year ago Thursday, and marks his first year as head of the National Defense Commission, the top government body, on Saturday. The birthday of his grandfather, Kim Il Sung, on Monday is the most important of the national holidays designed to cement loyalty to the ruling Kim family.

Whether this year's celebrations will include a missile launch or some other action that could escalate the tensions remains to be seen.

U.S. Secretary of State John Kerry, who arrived in Seoul on Friday for talks with South Korean officials, warned the North not to test fire a missile.

"If Kim Jong Un decides to launch a missile, whether it's across the Sea of Japan or some other direction, he will be choosing willfully to ignore the entire international community," Kerry told reporters.

He said the test would be a "huge mistake" for Kim.

A senior U.S military official told reporters there was no sign of military movements in the North and no real prospect of war. He spoke on condition of anonymity, saying he wasn't authorized to speak publicly about military intelligence.

But that doesn't mean North Korea won't put on some sort of a military show.

During last year's celebrations, North Korea failed in an attempt to send a satellite into space aboard a long-range rocket. The U.S. and its allies criticized the launch as a covert test of ballistic missile technology. North Korea tried again in December and succeeded. That was followed by the country's third underground nuclear test on Feb. 12.

Officials in Seoul and Washington say Pyongyang appears to be preparing to test fire a medium-range missile designed to be capable of reaching Guam. Foreign experts have dubbed the missile the "Musudan" after the northeastern village where North Korea has a launch pad, and say it has a range of 3,500 kilometers (2,180 miles).

A medium- or long-range missile test would be particularly significant because North Korea may now be capable of arming a ballistic missile with a nuclear warhead, the U.S. Defense Intelligence Agency concluded in an assessment revealed Thursday. Kerry refused to comment specifically Friday on that intelligence report, but said the North is still some time away from having a nuclear bomb that is "small, light and diversified."

South Korean officials have said they do not believe Pyongyang can place a nuclear warhead on a ballistic missile yet, but have put their military on high alert. Japan has also deployed PAC-3 missile interceptor units around Tokyo to protect its capital.

A Chinese city near the border with North Korea staged an air raid drill on Thursday amid the tensions, state media said. Authorities in Huichen, a city of 250,000 people in Jilin province, sounded alarms in residential areas and led participants to underground shelters, the China News Service reported.

It wasn't clear how long the drill had been planned or how many people took part. Calls to the city's spokesman and civil air defense office rang unanswered.

Kerry, who is also visiting China and Japan, is hoping to get Beijing to join the United States in pressuring Pyongyang.

China backed North Korea with troops during the 1950-53 Korean War and has been a major economic pipeline for the impoverished country. With little arable land, North Korea has struggled to feed its people, with two-thirds of the population of 24 million grappling with chronic food shortages, according to the World Food Program.

In Pyongyang on Friday, thousands of schoolchildren were amassed at Kim Il Sung Stadium for the induction of second-graders from around the country into the Korean Children's Union, one of the first steps into North Korea's political structure. They pledged to study hard and to build up strength to defend their nation. Retired military officers helped them tie on red scarves to complete the ritual.

"The U.S is our sworn enemy," said Ri So Hyang, a 13-year-old taking part in the ceremony. She said her brother had just enlisted. "I hope he'll fight well against the U.S. imperialists since I cannot."

Elsewhere around the city, workers tidied up buildings and roads alongside banners that read "Defend to the death" and called on citizens to become "human bombs" for leader Kim Jong Un.

Though few North Koreans have access to international media, and instead get their news from state media, they said they were aware of the tensions with the U.S.

At the flower exhibition, a guide called the current political situation "complicated."

"I don't know whether there will be a missile launch test, but if we do I think it will be just for national defense," Kim Jong Gum said. "And I think there's no need for other countries to try to tell us what to do and what not to do."

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Associated Press writers Jean H. Lee and Jon Chol Jin in Pyongyang; Bradley Klapper in Seoul, South Korea; and Kimberly Dozier and Robert Burns in Washington contributed to this report.