N. Korea threatens South anew

China calls for all parties to calm down but stands behind new U.N. sanctions The U.N. Security Council voted unanimously to approve new measures North Korea responds with a fresh statement of angry threats Analysts and officials warn that the spike in rhetoric is dangerous

(CNN) -- North Korea on Friday responded to tougher sanctions from the U.N. Security Council with another barrage of vitriol, repeating a vow to ditch all nonaggression pacts with the South.

A day after the isolated regime in Pyongyang had threatened a possible "preemptive nuclear attack" -- something analysts say they think it is unlikely and currently unable to do -- its official news agency reeled off a number of agreements with South Korea that it said would no longer apply.

It's the latest installment in a week of furious rhetoric from the North, fueled by its anger over the U.N. vote on the new sanctions, a response to the Pyongyang's recent nuclear test, and joint military drills by the United States and South Korea, which take place in the region each year.

North Korea watchers and U.S. officials say that the recent frenzy of ominous language from North Korea under its young leader Kim Jong Un makes the situation on the Korean Peninsula more worrying and unpredictable.

What to make of North Korea's newest threat .cnnArticleGalleryNav{border:1px solid #000;cursor:pointer;float:left;height:25px;text-align:center;width:25px} .cnnArticleGalleryNavOn{background-color:#C03;border:1px solid #000;float:left;height:25px;text-align:center;width:20px} .cnnArticleGalleryNavDisabled{background-color:#222;border:1px solid #000;color:#666;float:left;height:25px;text-align:center;width:25px} .cnnArticleExpandableTarget{background-color:#000;display:none;position:absolute} .cnnArticlePhotoContainer{height:122px;width:214px} .cnnArticleBoxImage{cursor:pointer;height:122px;padding-top:0;width:214px} .cnnArticleGalleryCaptionControl{background-color:#000;color:#FFF} .cnnArticleGalleryCaptionControlText{cursor:pointer;float:right;font-size:10px;padding:3px 10px 3px 3px} .cnnArticleGalleryPhotoContainer cite{background:none repeat scroll 0 0 #000;bottom:48px;color:#FFF;height:auto;left:420px;opacity:.7;position:absolute;width:200px;padding:10px} .cnnArticleGalleryClose{background-color:#fff;display:block;text-align:right} .cnnArticleGalleryCloseButton{cursor:pointer} .cnnArticleGalleryNavPrevNext span{background-color:#444;color:#CCC;cursor:pointer;float:left;height:23px;text-align:center;width:26px;padding:4px 0 0} .cnnArticleGalleryNavPrevNextDisabled span{background-color:#444;color:#666;float:left;height:23px;text-align:center;width:25px;padding:4px 0 0} .cnnVerticalGalleryPhoto{padding-right:68px;width:270px;margin:0 auto} .cnnGalleryContainer{float:left;clear:left;margin:0 0 20px;padding:0 0 0 10px} Soldiers in the North Korean army train at an undisclosed location on Wednesday, March 6, in a photo from the state-run Korean Central News Agency. North Korea has escalated its bellicose rhetoric, threatening nuclear strikes, just before the U.N. Security Council passed tougher sanctions against the secretive nation on Thursday, March 7. North Korean leader Kim Jong Un, center, poses with chiefs of branch social security stations in this undated picture released by North Korea's official news agency on November 27, 2012. Kim celebrates with staff from the satellite control center in Pyongyang, North Korea, during the launch of a rocket carrying a satellite, in a photo released by the official North Korean news agency on December 12. A crowd watches as statues of the nation's founder, Kim Il Sung, and his son Kim Jong Il are unveiled during a ceremony in Pyongyang on April 13, 2012. Photos from North Korea are rare, but the country was on full display in April 2012 as it celebrated the 100th birthday of Kim Il Sung. A North Korean soldier stands guard in front of an Unha-3 rocket at the Tangachai-ri Space Center on April 8, 2012. A military vehicle participates in a parade in Pyongyang on April 15, 2012. North Koreans wave flags in front of portraits of Kim Il Sung, left, and his son Kim Jong Il during celebrations to mark the 100th birth anniversary of Kim Il Sung in Pyongyang on April 16, 2012. North Korean soldiers relax at the end of an official ceremony attended by leader Kim Jong Un at a stadium in Pyongyang on April 14, 2012. Kim Jong Un applauds as he watches a military parade in Pyongyang on April 15, 2012. A North Korean soldier stands on a balcony in Pyongyang on April 16, 2012. North Korean soldiers march during a military parade in Pyongyang on April 15, 2012. Soldiers board a bus outside a theater in Pyongyang on April 16, 2012. North Korean performers sit below a screen showing images of leader Kim Jong Un in Pyongyang on April 16, 2012. North Korean soldiers salute during a military parade in Pyongyang on April 15, 2012. Kim Jong Un visits the Rungna People's Pleasure Ground, which is under construction in Pyongyang, in a photo released on July 3, 2012, by North Korea's official Korean Central News Agency. North Korean soldiers listen to a speech during an official ceremony attended by leader Kim Jong Un at a stadium in Pyongyang on April 14, 2012. Members of a North Korean military band gather following an official ceremony at the Kim Il Sung stadium in Pyongyang on April 14, 2012. North Korean military personnel watch a performance in Pyongyang on April 16, 2012. A North Korean controller is seen along the railway line between Pyongyang and North Pyongan province on April 8, 2012. A North Korean military honor guard stands at attention at Pyongyang's airport during a diplomatic visit on May 2, 2001. 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South Korea has warned the North that it will retaliate strongly and sternly if its citizens are threatened.

"This surge in provocative rhetoric is particularly dangerous," said Michael Auslin of the American Enterprise Institute. "South Korea's new president (Park Geun Hye) can't be seen to back down in the face of the North's threats, while Kim Jong Un may feel that his successful missile and nuclear tests give him the ability to keep pressuring Seoul. The two may wind up talking themselves into conflict."

South Korean President Park Geun-hye, who took office late last month, said Friday that Seoul would respond strongly to any provocation from Pyongyang, the semiofficial news agency Yonhap reported.

The possibility of flare up was highlighted by the Washington-based Center for Strategic and International Studies, which predicted a provocative move from the North "in the coming weeks."

The center said that according to its research, Pyongyang has carried out "a military provocation of some form within weeks of every South Korean presidential inauguration dating back to 1992."

A military clash could risk drawing in the United States, which has about 28,500 troops stationed in South Korea as part of the security alliance between the two countries.

The most recent skirmish between the two Koreas took place in November 2010, when the North shelled an island on the South's side of the border, killing several people. Pyongyang claimed Seoul had provoked it by carrying out training exercises off their shared coast.

A week of strong threats

The North's comments Friday doubled down on statements it had made earlier this week, promising to abolish the armistice agreement that stopped the Korean War in 1953, and threatening strikes on the United States and South Korea.

Claiming its enemies are "hell bent on confrontation and war fever," Pyongyang said it was now revoking "all agreements on nonaggression reached between the north and the south," a declaration it has made in previous years

It also said it was nullifying the joint declaration on the denuclearization of the Korean Peninsula. The North, which conducted its third underground nuclear test last month, had said recently that denuclearization of the region was "impossible" because of what it described as the United States' hostile policy toward it.

And it stated that it was immediately cutting off the "north-south hotline," three days after it had already said it planned to terminate its military telephone line with the United States.

The phone line is meant to serve as a tool to defuse potential flash points along the heavily militarized border between the two Koreas.

But Andre Kok, deputy public affairs officer for U.S. Forces in Korea, said that reports of the North's Korean People's Army (KPA) cutting off communication often arise when military training exercises are taking place, as they are at the moment.

"When we place a call on the direct phone line and the KPA does not answer, we have no way of knowing if the KPA has actually disconnected the phone lines or are just not answering the phone," he said.

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New U.N. measures

Tensions are particularly high at the moment because of the new measures against the North adopted unanimously Thursday by the U.N. Security Council.

"These sanctions will bite, and bite hard," U.S. Ambassador to the United Nations, Susan Rice, said after the vote.

China, North Korea's key ally, could have used its veto power to block the sanctions. Instead, after weeks of negotiating, it signed on to the final draft.

"China is a country of principle," China's U.N. Ambassador Li Baodong said. "We are firmly committed to safeguarding peace and stability on the Korean peninsula."

On Friday, China's Foreign Ministry called upon "all relative parties to stay calm and refrain from taking actions that may escalate tension." Spokeswoman Hua Chunying reiterated China's support for the sanctions, which have stoked Pyongyang's fury.

The goal of the new sanctions is to stymie the activities of North Korean banks and cash couriers who might be funneling money to the secretive regime's nuclear and missile programs.

It will be tougher for the regime to move large sums of cash stuffed into suitcases, Rice said.

The U.N. resolution also outlines measures to step up scrutiny of suspicious sea shipments and air cargo. And it expands restrictions to encompass several institutions and senior officials in the North's weapons industry, as well as a range of materials and technology known to be used in uranium enrichment.

It also blocks the sale of luxury goods -- such as yachts and certain high-end jewelry -- to North Korea.

"As a result, North Korea's ruling elite, who have been living large while impoverishing their people, will pay a price" for the ongoing nuclear activities, Rice said.

Questions over sanctions' effectiveness

Some doubt whether the new measures will make much difference.

Sanctions imposed after previous nuclear tests and rocket launches have failed to deter Pyongyang.

China will go a long way toward determining whether the new sanctions really do have "bite," analysts say.

"As long as China allows North Korea to operate, as long as China provides food, energy assistance, and investment, the sanctions really don't matter," said Doug Bandow of the Cato Institute.

North Korea notoriously allows many of its people to live in malnutrition and starvation. Still, the country needs a functioning economy, partly to finance its military, Bandow explained.