Mehdi Ghasemi / ISNA via AP, file

Two technicians in Iran adjust their protective wear alongside a container of yellow cake uranium.

Iran said on Tuesday it had started production at two uranium mines and a yellow-cake plant, declaring that Western opposition would not slow its nuclear program days after talks between Tehran and world powers failed to reach an accord.

The country opened the Saghand 1 and 2 uranium mines in the central city of Yazd, which will extract uranium from a depth of more than 1,100 feet, and the Shahid Rezaeinejad yellow-cake plant at Ardakan to mark Iran's National Nuclear Technology Day, state news agency IRNA said.

The Ardakan plant is capable of producing 66 tons of yellow cake -- raw uranium -- annually, IRNA said.

The United States and some allies suspect Iran is pursuing a nuclear weapons capability, but Iran insists that its atomic program, including its enrichment of uranium, is for purely peaceful purposes. Talks between Iran and world powers held in Kazakhstan last week failed to reach a breakthrough.

"They [world powers] tried their utmost to prevent Iran from going nuclear, but Iran has gone nuclear," Iranian President Mahmoud Ahmadinejad said in a speech at Iran's Atomic Energy Organization on Tuesday.

"This nuclear technology and power and science has been institutionalized. … All the stages are in our control, and every day that we go forward a new horizon opens up before the Iranian nation."

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SEOUL -- Staff at embassies in North Korea appeared to be remaining in place on Saturday despite an appeal by authorities in Pyongyang for diplomats to consider leaving because of heightened tension after weeks of bellicose exchanges.

North Korean authorities told diplomatic missions they could not guarantee their safety from next Wednesday -- after declaring that conflict was inevitable amid joint U.S.-South Korean military exercises due to last until the end of the month.

Whatever the atmosphere in Pyongyang, the rain-soaked South Korean capital, Seoul, was calm. Traffic moved normally through the city center, busy with Saturday shoppers.

South Korea's Yonhap news agency quoted a government official as saying diplomats were disregarding the suggestion they might leave the country.

"We don't believe there's any foreign mission about to leave Pyongyang," the unidentified official was quoted as saying. "Most foreign governments view the North Korean message as a way of ratcheting up tension on the Korean peninsula."

North Korea has been angry since new U.N. sanctions were imposed following its third nuclear weapons test in February. Its rage has apparently been compounded by joint U.S.-South Korean military exercises that began on March 1.

China's Xinhua news agency on Friday had quoted the North's Foreign Ministry as saying the issue was no longer whether but when a war would break out.

Most countries saw the appeal to the missions as little more than strident rhetoric after weeks of threatening to launch a nuclear strike on the United States and declarations of war against the South.

But Russia said it was "seriously studying" the request.

'Deeply concerned'
A South Korean government official expressed bewilderment.

"It's hard to define what is its real intention," said the official, who asked not to be identified. "But it might have intensified these threats to strengthen the regime internally or to respond to the international community."

The United Nations said its humanitarian workers remained active across North Korea. Secretary General Ban Ki-Moon, however, remained "deeply concerned" about tensions, heightened since the imposition of U.N. sanctions against the North for its third nuclear arms test last in February.

The appeal to diplomats followed news reports in the South that North Korea, under its 30-year-old leader Kim Jong-un, had moved two medium-range missiles to a location on its east coast.

That prompted the White House to say that Washington would "not be surprised" if the North staged another missile test.

Kim Jong-un is the third member of his dynasty to rule North Korea. He took over in December 2011 after the death of his father, Kim Jong-il, who staged confrontations with South Korea and the United States throughout his 17-year rule.

North Korea has always condemned the exercises held by U.S. forces and their South Korean allies. But its comments have been especially vitriolic this year as the United States dispatched B-2 bombers from its home bases to stage mock runs.

North Korea's government daily newspaper said tension remained high because the United States was "waging madcap nuclear war maneuvers.”

"This is aimed at igniting a nuclear war against it through a pre-emptive strike," the Minju Joson said in a commentary. "The prevailing situation proves that a new war, a nuclear war, is imminent on the peninsula."

But some commentators examining the outcome of meetings in Pyongyang last week - of the ruling Workers' Party and of the rubber-stamp legislature - concluded that Kim and his leadership were more concerned with economic than military issues. 

Internet site 38 North, which specializes in North Korean affairs, noted the reappointment of reformer Pak Pong Ju as prime minister, the limited titles given to top military and security officials and the naming of a woman to a senior party post.

"These personnel appointments make a great deal of sense in the context of Pyongyang's declarations ... that its economic policy will be modified by introducing systemic reforms while also continuing the development of nuclear weapons," 38 North commentator Michael Madden wrote.

"(They) appear to be important steps in moving key economic development products and production away from the control of the military to the party and government,” he added.

North Korea has not shut down one symbol of joint cooperation, the Kaesong industrial zone just inside its border. But last week it prevented South Koreans from entering the complex and about 100 of them who have since remained were due to return home on Saturday, leaving a further 500 there. 

Slideshow: Daily life in North Korea

Elizabeth Dalziel / AP

From work to play, see pictures from inside the secretive country.

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Shamil Zhumatov / Reuters

Iran's chief nuclear negotiator Saeed Jalili prays at a mosque in Almaty, Kazakhstan, on Friday.

News analysis

ALMATY, Kazakhstan -- An air of cautious optimism hung over Almaty, Kazakstan, on Friday as Western and Iranian negotiators began the first day of another round of nuclear talks.

After Friday’s talks had ended for the day, however, a Western diplomat said the sides still had work to do.

"We had a long and substantial discussion on the issues, but we remain a long way apart on the substance,” the diplomat said. “We are now evaluating the situation and will meet again tomorrow."

The six powers – the United States, Russia, China, France, Britain and Germany – met Iranian officials with the aim of settling a decade-long tussle over Tehran's nuclear program.

Iran has resisted pressure -- and hardening economic sanctions -- for years arguing its uranium enrichment program is for peaceful purposes and therefore should be allowed to continue.

During the last meetings in February, the world powers appeared to have watered down their demands and offer mild relief to sanctions that have been strangling Iran’s economy.

Western diplomats were hoping for a discussion of the specific points of their proposals, such as closing a nuclear facility and shipping some enriched uranium stockpiles abroad in return for easing some sanctions.

Iranian officials were caught off guard by what many view as the West’s relatively generous offer.

“For the first time during any of the international nuclear talks, we witnessed signals that the other side is acting in good faith,” Iran’s foreign minister Ali Akbar Salehi told a news conference in Tehran on March 10, referring to the last discussions also held in Almaty.

“We hope they continue to do so,” he added.

Western diplomats, speaking on the condition of anonymity after the February talks, also said they were cautiously optimistic. 

This attitude comes after a string of failed talks.

Both sides have accused the other of not being realistic or serious about wanting to make a deal. Throughout, the West has charged Iran with delaying tactics, and of saying one thing then doing another. 

Both sides are in a sticky spot. 

President Barack Obama came to office on a mandate to end two wars, not to open up another front. So military action against Iran to halt a nuclear weapons program could prove unpopular in the United States. 

Slideshow: Everyday life in Iran

At schools, in shops, and on the streets of big cities and small towns, daily life plays out in Iran.

Launch slideshow

Iran is also walking a tightrope: Israel has consistently said its patience with diplomacy is running out and it may resort to military strikes on Iran.

Tehran is also under pressure from sanctions. The economic distress could spill over into massive street protests, something the government definitely does not want to see in the run-up to June elections. 

Yet another issue that hangs over talks: the war in Syria.  

Iran is one of the Syrian government’s most important backers: Several senior Iranian military officials have already been killed in Damascus. Syrian rebels have accused the West of standing by as the regime of Bashar Assad kills tens of thousands of his own citizens. 

Obama’s reluctance to arm the rebels in Syria is partly because it would scupper negations with Iran over its nuclear program, according to foreign policy experts and some Western diplomats. 

Reuters contributed to this report.

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This story was originally published on Fri Apr 5, 2013 10:56 AM EDT

TEPCO via EPA

Attempts stop rats getting inside a reactor at the Fukushima Daiichi nuclear power plant led to a cooling system shutdown. Debris on the fuel rack in a spent-fuel pool is seen in this handout photograph taken in mid-February.

TOKYO -- A cooling system at a tsunami-damaged nuclear plant in Japan failed Friday for the second time in a month after an outage caused by construction work to keep out rats suspected of setting off the earlier blackout.

Power for the cooling system for a storage pool for fuel was restored after a two-hour break at reactor No. 3, and there was no immediate danger from the breakdown, according to Tokyo Electric Power Co., the utility that operates Fukushima Daiichi in northeastern Japan.

TEPCO via Reuters

A dead rat is seen near a temporary switchboard used to supply power to cooling systems at three fuel pools in the Fukushima facility in this handout photograph taken on March 20.

Work to put up nets to keep out rats and other animals at Fukushima Daiichi plant in northeastern Japan inadvertently caused the power outage, TEPCO spokesman Akitsuka Kobayashi said. Details were not clear, and the outage was still under investigation.

A dead rat found near a switchboard was suspected of the power outage last month that led to a cooling system not working for two days at the plant.

Nuclear Regulation Authority spokesman Takahiro Sakuma said an alarm went off in the afternoon about the latest problem at reactor No. 3.

Multiple meltdowns
The cooling system can be turned off for two weeks before temperatures approach dangerous levels at the spent fuel storage pools.

But if the water runs dry, the fuel rods, even spent ones, will spew enormous levels of radiation.

The plant went into multiple meltdowns after the March 2011 tsunami damaged backup generators and all cooling systems failed, including those for the reactors.

The plant is being decommissioned, but continues to have glitches.

Fears are growing about the safety of nuclear plants, and people have periodically staged streets protests that are rare in Japan.

Only two of the nation's 50 working power plants are up, and the government is running beefed up safety checks on the plants, including scrutinizing quake faults right below or near the plants.

Shinzo Abe, who became prime minister about three months ago, has expressed a desire to restart nuclear plants.

Japan lacks natural resources and relied on nuclear energy for about a third of its electricity needs prior to March 2011. Energy imports have soared over the last two years, putting a strain on the economy.

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This story was originally published on Fri Apr 5, 2013 8:13 AM EDT

VICE via Reuters file

North Korean leader Kim Jong Un and former NBA star Dennis Rodman watch an exhibition basketball game in Pyongyang, North Korea, on Feb. 28.

North Korean media calls Kim Jong Un "the greatest-ever commander." Dennis Rodman says he is "a normal guy."

Neither description seems fitting, but little is known about the third-generation leader now locked in a showdown with the U.S. and South Korea that some fear could lead to war.

Before Kim took over from his father, Kim Jong Il, he had barely been seen in public. And even though he's been in charge for more than a year, there's been only a trickle of information about his personality and habits.

The most recent details about the man threatening to send missiles to the U.S. come from Rodman, who made a trip to Pyongyang earlier this year. Here are some tidbits about Kim that have emerged outside the North Korean propaganda machine:

He shares a birthday with Elvis Presley ... maybe: Kim has been reported to be somewhere between 29 and 30 years old. But Kenji Fujimoto, a sushi chef who worked for his family until 2001 and later wrote a tell-all, claims he was born Jan. 8, 1983 — the same date as The King.

KCNA via Reuters file

Kim Jong Un and wife Ri Sol-Ju last July.

He has a first lady: North Korean media revealed Kim was married last July when it announced his fashionable female companion at the opening of an amusement park was his wife, Ri Sol-ju. No one is certain when they tied the knot or whether they have children. South Korean media say she's a former cheerleader and singer. 

He was educated in the West: Kim attended a state school in Switzerland from 1998 to 2000, posing as a diplomat's son named Pak Un, according to the Washington Post. "I never saw his father or mother," Principal Peter Burri told the paper. Another official described him as "well-integrated, diligent, ambitious." Kim reportedly later attended the Kim Il Sung Military University in Pyongyang, named after his grandfather.

He's crazy about basketball: He idolized Michael Jordan and was no slouch on the court himself. One high-school buddy described him as "explosive" and a "playmaker." Another said he was fiercely competitive: "He hated to lose."

KCNA via EPA

Kim Jong Un and his iMac.

He's brand-conscious: Teenage buddies recalled he had a collection of expensive Nike sneakers. A recent photo of him plotting military action against the U.S. showed an Apple iMac computer on his desk. His wife supposedly carries a Dior clutch, though some think it's a knock-off.

His hairstyle is unsanctioned: North Korea reportedly has 28 "recommended" hairstyles for its people. Kim's 'do — shaved on the sides, floppy on top — is not among them, according to a Hong Kong TV network that obtained photos of the approved looks.

He's a song-and-dance man: High-school classmates told London's Daily Telegraph his favorite song was "Brother Louie" by the German pop duo Modern Talking. Rodman told London's Sun that Kim digs 1980s disco. "There was an all-girl band playing and we were definitely getting down," Rodman said of their visit.

KCNA via Reuters

Kim Jong Un looks at a photo of his grandfather Kim Il Sung last month.

He's a heavyweight: South Korea's Yonhap news agency has reported that after the 2004 death of his mother from cancer, Kim went on a drinking and eating binge, ballooning to almost 200 pounds. He remains plump in a country ravaged by famine and suffers from diabetes and hypertension.

He's a chip off the old block: Kim looks so much like his grandfather, national founder Kim Il Sung, that North Korea's official news agency had to deny rumors he had gone under the knife. Analysts say he hoped to model himself on his grandfather, who was more liked by his people than Kim's much-feared father.

Slideshow: North Korea's young leader, Kim Jong Un

The youngest son of Kim Jong Il succeeded his late father in 2011, becoming the third member of his family to rule the unpredictable and reclusive communist state.

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North Korea is moving a medium-range missile to a site in the east of the country, a U.S. intelligence official said Thursday as tensions with the nuclear-armed state continued to escalate.

The official declined to say where the Musudan missile was headed, but the North has used a site near the Russian border on the coast for its missile tests in the past.

South Korean Defense Minister Kim Kwan-jin told lawmakers Thursday that the missile had "considerable range" but not enough to hit the U.S. mainland, according to The Associated Press.

The news came hours after North Korea's military warned that it had been authorized to attack the U.S. using "smaller, lighter and diversified" nuclear weapons -- the latest in a string of war cries against America in recent weeks.

"The moment of explosion is approaching fast,” the military statement said.

Tensions on the Korean Peninsula rose in December when the North test-fired a rocket and increased again when it tested a nuclear bomb in February.

Russia joined the ranks of countries voicing concern at the escalating crisis, saying the North's disregard for United Nations’ restrictions was unacceptable.

The U.S. is sending an advanced anti-ballistic missile system to Guam to protect American military sites, officials said Wednesday.

The Terminal High-Altitude Area Defense system is expected to arrive at the U.S. territory in the Pacific within two weeks.

'Real and clear danger'
Defense Secretary Chuck Hagel said the North’s provocations were "a real and clear danger and threat" to U.S. interests and stressed that Washington was taking them seriously.

"We are doing everything we can ... to defuse that situation on the peninsula," Hagel said after a speech Wednesday at the National Defense University at Fort McNair in Washington, D.C.

"I hope the North will ratchet this very dangerous rhetoric down," he said, adding that there is a pathway to peace but only if Pyongyang decides to be "a responsible member of the world community."

On Thursday, North Korea warned its military had been authorized to carry out "cutting-edge, smaller, lighter and diversified" nuclear strikes to protect itself against the United States.

"The moment of explosion is approaching fast. No one can say a war will break out in Korea or not and whether it will break out today or tomorrow," read the statement of an unnamed military spokesman.

The statement, which was carried by the state-run Korean Central News Agency (KCNA), informed the White House and the Pentagon that "the merciless operation of its revolutionary armed forces in this regard has been finally examined and ratified."

It also made reference to U.S. jet sorties over the Korean Peninsula, which Pentagon officials have said are part of routine, joint military drills with South Korea.

"The U.S. high-handed hostile policy toward the DPRK aimed to encroach upon its sovereignty and the dignity of its supreme leadership and bring down its social system is being implemented through actual military actions without hesitation," the North’s statement read.

Meanwhile, a former U.N. official who visited North Korea last year reported that officials there said they could restart the Yongbyon reactor in three months. That is significantly quicker than many U.S. nuclear experts believe a restart would take.

U.S. officials said they did not believe the operation would be a huge engineering challenge.

A restart would, however, be significant, as it would give North Korea the capability to make weapons-grade plutonium again. The reactor was shut down in 2007.

"North Korea's assertion that it intends to bring Yongbyon back online can't be easily written off as an insurmountable hurdle," one U.S. official said.

The Associated Press and NBC News' Marc Smith, Alastair Jamieson, Andrea Mitchell and Becky Bratu contributed to this report.

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This story was originally published on Thu Apr 4, 2013 4:17 AM EDT

North Korea escalated its provocative rhetoric on Thursday, warning that its military is authorized to wage "cutting-edge smaller, lighter and diversified" nuclear strikes to protect against the United States.

"The moment of explosion is approaching fast. No one can say a war will break out in Korea or not and whether it will break out today or tomorrow," read the statement of an unnamed military spokesman.

The statement, which was carried by the state-run Korean Central News Agency (KCNA), informs the White House and the Pentagon that "the merciless operation of its revolutionary armed forces in this regard has been finally examined and ratified."

The warlike rhetoric is the latest escalation in a series of threats from Pyongyang, which claims the joint U.S. and South Korean military exercises taking place in the South are in preparation for an invasion.

"The U.S. high-handed hostile policy toward the DPRK aimed to encroach upon its sovereignty and the dignity of its supreme leadership and bring down its social system is being implemented through actual military actions without hesitation," the military statement read.

The United States says the exercises are routine military drills.

Defense Secretary Chuck Hagel said Wednesday that North Korea's provocations are "a real and clear danger and threat" to U.S. interests and Washington is taking them seriously.

"We are doing everything we can ... to defuse that situation on the peninsula," Hagel said after a speech at the National Defense University at Fort McNair in Washington, D.C.

"I hope the North will ratchet this very dangerous rhetoric down," he said, adding that there is a pathway to peace but only if Pyongyang decides to be "a responsible member of the world community."

U.S. response

The U.S. has responded to the diplomatic crisis with more than words, dispatching two warships to the western Pacific to be on alert for missiles and conducting bomber and fighter flyovers.

Defense officials also said an advanced anti-ballistic missile system will be sent to the U.S. military base in Guam in response to North Korean threats targeting Guam and U.S. military facilities in the region.

The system -- which includes missiles, launchers, radar and communications -- is expected to arrive within two weeks.

A former UN official who visited North Korea last year reports that officials there said they could re-start the Yongbyon reactor in three months.

That is a lot shorter than many U.S. nuclear experts believe a re-start would take.

U.S. officials tell NBC News that no matter what the timeline is, they don't believe the operation would be a huge engineering challenge. A re-start would, however, be significant, as it would give North Korea the capability to make weapons-grade plutonium again. The reactor was shut down in 2007.

"North Korea's assertion that it intends to bring Yongbyon back on line can't be easily written off as an insurmountable hurdle," said one U.S. official.

Asked how long a re-start might take, U.S. intelligence officials declined to provide any details. 

Banning South Korean workers
North Korean leader Kim Jong Un has shown no inclination to back off yet. The rogue nuclear state's latest move was banning South Korean workers from the jointly run Kaesong industrial zone.

Seoul said about 800 South Koreans who had stayed overnight at the complex were being allowed to return home, but that new workers were not being allowed across the border.

Kaesong, a major source of income for the impoverished, communist North, is home to 124 South Korean companies that employ 53,000 North Korean workers in a cross-border, heavily fortified joint enterprise. Permission is granted on a daily basis for South Korean workers to cross into the complex, situated in the North, the BBC reported.

"South Korea's government deeply regrets the entry ban and urges it be lifted immediately," South Korea official Kim Hyung-seok told reporters Wednesday.

China expressed "serious concern" to U.S. diplomats over the worsening crisis. A Chinese official met ambassadors from the United States and both Koreas, expressing hope that Pyongyang and Seoul could resolve their differences through talks, China’s foreign ministry spokesman Hong Lei said, according to Reuters and Voice of America reporter Steve Herman.

Russia also voiced concern about North Korea's military apparatus, saying human error or technical malfunction may cause the situation on the Korean Peninsula “to go out of control,” according to a report Wednesday on Russian news service Interfax.

The comments came after Secretary of State John Kerry denounced North Korea's increasingly threatening rhetoric as "unacceptable," and said the U.S. would defend its allies, South Korea and Japan, from any threat from the North.

During a joint news conference with South Korea's foreign minister at the State Department on Tuesday, Kerry said North Korea knows what it needs to do if it wants to resume dialogue with the rest of the world.

NBC News' Andrea Mitchell and Becky Bratu contributed to this report.

Slideshow: Glimpses into the hermit kingdom of North Korea

David Guttenfelder / AP

As chief Asia photographer for the Associated Press, David Guttenfelder has had unprecedented access to communist North Korea. Here's a rare look at daily life in the secretive country.

Launch slideshow

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This story was originally published on Wed Apr 3, 2013 5:03 AM EDT

One of North Korea's top decision-making bodies is setting guidelines that call nuclear weapons "the nation's life" that won't be traded even for "billions of dollars,” The Associated Press reported.

The statement Sunday came after a plenary meeting of the central committee of the ruling Workers' Party attended by leader Kim Jong Un and other officials, the AP said.

It also followed a declaration on Saturday that it was entering a "state of war" with South Korea, the latest in a string of increasingly belligerent outbursts from the isolated state.

Sunday’s statement says nuclear weapons aren't "goods for getting U.S. dollars" or a "political bargaining chip." Outside analysts have said Pyongyang raises worries over its nuclear ambitions to spur nuclear-disarmament-for-aid talks, the AP said.

Slideshow: Glimpses into the hermit kingdom of North Korea

David Guttenfelder / AP

As chief Asia photographer for the Associated Press, David Guttenfelder has had unprecedented access to communist North Korea. Here's a rare look at daily life in the secretive country.

Launch slideshow

It said Pyongyang will also increase work to build up the economy. Kim has made fixing the moribund economy a focus.

On Thursday the U.S. sent two nuclear-capable bombers to South Korea, where they dropped inert munitions in a military exercise. The flight sparked an angry response from the North, which declared on Friday that it was preparing rockets aimed at American bases in South Korea and the Pacific.

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This story was originally published on Sun Mar 31, 2013 9:38 AM EDT

North Korea said on Saturday that it was entering a "state of war" with South Korea, following a call to arms by the country's young leader Kim Jong Un and days of increasingly belligerent rhetoric from the isolated state.

The North's official news agency KCNA published the joint statement issued by the government, political parties and other organizations.

"From this time on, the North-South relations will be entering a state of war and all issues raised between the North and the South will be handled accordingly," it said. 

The statement also warned that if the U.S. and South Korea carried out a pre-emptive attack, the conflict "will not be limited to a local war, but develop into an all-out war, a nuclear war."

Analysts have said the North's threats have followed a similar pattern but that the country's 30-year-old leader is unpredictable and potentially dangerous.

The White House responded on Saturday by reiterating that "North Korea has a long history of bellicose rhetoric and threats," National Security Council spokeswoman Caitlin Hayden said in a statement. However, she said the U.S. "takes these threats seriously".

"We continue to take additional measures against the North Korean threat, including our plan to increase the U.S. ground-based interceptors and early warning and tracking radar, and the signing of the ROK-U.S. counter-provocation plan," she said.

Slideshow: Glimpses into the hermit kingdom of North Korea

David Guttenfelder / AP

As chief Asia photographer for the Associated Press, David Guttenfelder has had unprecedented access to communist North Korea. Here's a rare look at daily life in the secretive country.

Launch slideshow

On Thursday the U.S. sent two nuclear-capable bombers to South Korea, where they dropped inert munitions in a military exercise. The flight sparked an angry response from the North, which declared on Friday that it was preparing rockets aimed at American bases in South Korea and the Pacific.

A South Korean defense ministry official said there were no early signs that the North was mobilizing, Reuters reported.

The two nations have technically been at war since a truce ended their 1950-53 conflict, but tensions have been increasing since the North carried out its third nuclear weapons test in February.

NBC News' Kristen Welker and Reuters contributed to this report.

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PhotoBlog: Pyongyang marchers: 'Rip the puppet traitors to death!'