As US and South Korean troops braced for what some feared may be an imminent North Korean missile launch, US secretary of state John Kerry arrived in Seoul on Friday for talks with South Korean officials before continuing on to China.
Hours earlier, President Barack Obama demanded an end to the escalating war rhetoric from Pyongyang. In his first public comments since North Korea warned of a nuclear war on the Korean Peninsula, Obama called it time for the isolated nation "to end the belligerent approach they have taken and to try to lower temperatures."
"Nobody wants to see a conflict on the Korean Peninsula," Obama said on Thursday, speaking from the Oval Office alongside UN secretary-general Ban Ki-moon.
North Korea has not specified plans to fire a missile or carry out another nuclear test, but has warned that it has weapons on standby and would be prepared to strike if provoked by the US and South Korea, its Korean War foes.
The torrent of war cries is seen outside Pyongyang as an effort to raise fears and pressure Seoul and Washington into changing their North Korea policies, and to show the North Korean people that their young leader is strong enough to stand up to powerful foes.
US and South Korean troops have been conducting annual joint military drills in the South since early March, including bringing out nuclear-capable stealth bombers and fighter jets in what the Air Force acknowledged was a deliberate show of force.
The escalation of tensions comes as North Korea is celebrating a slew of first 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 on Thursday, and will mark his first year as head of the National Defense Commission, the top government body, on Saturday.
North Koreans also have begun celebrating the April 15 birthday of Kim's grandfather, Kim Il Sung. The birthday is considered the most important of national holidays designed to cement loyalty to the ruling Kim family.
At Mansu Hill, where massive bronze statues of the two late leaders overlook the city, Pyongyang citizens were busy scrubbing the steps up to the plaza with soap and water to prepare for the stream of people who will be paying their respects to the Kims.
At Kim Il Sung Stadium, schoolchildren being inducted into the Korean Children's Union, a political organization for young North Koreans, pledged to study hard and to build up strength to defend their nation. Retired military officers helped them tie on red scarves to help complete the ritual.
No military parade or mass events are expected, but North Korea has used major holidays to show off its military power. Analysts say Pyongyang could well mark the occasion with a provocative missile launch.
"However tense the situation is, we will mark the Day of the Sun in a significant way," Kim Kwang Chon, a Pyongyang citizen, told The Associated Press, referring to the April 15 birthday. "We will celebrate the Day of the Sun even if war breaks out tomorrow."
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.
Another try 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 long-range missile.
On Thursday, North Korea claimed to have "powerful striking means" on standby. The Committee for the Peaceful Reunification of the Fatherland, a nonmilitary agency that deals with relations with South Korea, said the coordinates of targets have been "put into warheads." It didn't clarify, but the language suggested a missile.
Newly revealed US intelligence shows Washington believes North Korea may now be capable of arming a ballistic missile with a nuclear warhead. However, the weapon wouldn't be very reliable, the US Defense Intelligence Agency concluded in an assessment was revealed on Thursday at a public hearing in Washington.
However, South Korea believes that Pyongyang does not yet have a nuclear device small enough to put on a missile, defense ministry spokesman Kim Min-seok said in response to a question about the DIA assessment.
"Our military's assessment is that North Korea has not yet miniaturized" a nuclear device, Kim said in Seoul.
South Korean unification minister Ryoo Kihl-jae urged Pyongyang to engage in dialogue and reverse its decision to pull workers from a joint industrial park just north of their shared border, a move that has brought South Korean factories in Kaesong to a standstill.
As Kerry headed to Asia, he and his top aides discussed how to get China to join the United States in putting pressure on Pyongyang, according to a senior administration official who was present at the meeting.
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.
"If anyone has real leverage over the North Koreans, it is China," James Clapper, the U.S. director of national intelligence, told Congress on Thursday. "And the indications that we have are that China is itself rather frustrated with the behavior and the belligerent rhetoric of ... Kim Jong-un."
He called North Korea's threats "belligerent rhetoric" and noted that things are not as tense as past confrontations between the US and North Korea.
Referring to Kim Jong-un, he said on Thursday: "I don't think ... he has much of an endgame other than to somehow elicit recognition," and to turn the nuclear threat into "negotiation and to accommodation and presumably for aid."
Since taking power, Kim has pledged to end the era of "belt-tightening" in North Korea by placing his focus on reviving the economy. But he also has enshrined the drive to build nuclear weapons as a key national goal, billed in Pyongyang as a necessary defense against what North Koreans see as a persistent U.S. nuclear threat.
North Korea has spent decades trying to perfect a multistage, long-range delivery means for a nuclear bomb aimed at threatening the U.S., analysts say.
Pyongyang has acknowledged attempts to launch satellites into space aboard long-range rockets in 1998, 2009 and twice in 2012. North Korea also regularly stages short-range missile tests, and in 2006 a long-range missile launch broke apart shortly after liftoff.
North Korea says its rocket launches are part of a peaceful space program. But the U.N., Washington and others called the launches veiled tests of technology that can be used in ballistic missiles.
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).
Such a launch would violate U.N. Security Council resolutions prohibiting North Korea from nuclear and ballistic missile activity, and mark a major escalation in Pyongyang's standoff with neighboring nations and the United States. North Korea already has been punished by new U.N. sanctions for the December rocket launch and February nuclear test.
Analysts do not believe North Korea will stage an attack similar to the one that started the Korean War in 1950. But there are concerns that the animosity could spark a smaller-scale skirmish.
The Korean War ended in 1953 with a truce, not a peace treaty, and the U.S. and North Korea do not have diplomatic relations. Seeking a peace treaty and reunification of the Korean Peninsula has been a major goal of all three Kims.