Story highlights South Korea doesn't consider latest threat "new," its unification ministry says

North Korea threatens "all-out war and nuclear war" on its enemies, state news reports

"We will first target and dissolve" the mainland U.S., Hawaii and Guam, the report adds

Pyongyang has been defiant in the face of efforts to halt its nuclear program

North Korea has entered a "state of war" with neighboring South Korea, according to a report Saturday from the state-run Korean Central News Agency that included a threat to "dissolve" the U.S. mainland.

"Any issues regarding North and South will be treated in accordance to the state of war," North Korea's government said in a special statement carried by KCNA. "... The condition, which was neither war nor peace, has ended."

North Korea and South Korea technically remain at war since their conflict between 1950 and 1953 ended with an armistice and not a peace treaty. On March 11, the North Korean army declared the armistice agreement invalid.

This report represented Pyongyang's latest salvo aimed at South Korea and its ally the United States. Tensions in the area have been ratcheting up for months, with North Korea remaining defiant and, in some opinions, belligerent in the face of international efforts to halt its nuclear program.

Saturday's report included a direct threat to the United States, while also asserting Pyongyang "will not limit (itself) to limited warfare but to all-out war and nuclear war."

"We will first target and dissolve mainland United States, Hawaii and Guam, and United States military based in South Korea. And the (South Korean presidential office) will be burned to the ground," the KCNA report said.

In a statement later Saturday, South Korea did not treat their neighbor's latest threat as anything new.

Seoul noted scores of its personnel had entered the Kaesong Industrial complex -- a joint economic cooperation zone between the two Koreas situated on the North's side of the border -- on Saturday morning with hundreds more set to join them later in the day, seemingly suggesting they were going about business as usual.

"The announcement made by North Korea is not a new threat, but part of follow-up measures after North Korea's supreme command's statement that it will enter the highest military alert" on Tuesday, South Korea's Unification Ministry said in a statement.

Map appears to show U.S. targets

A day earlier, same official North Korean news agency reported its leader Kim Jong Un had approved a plan to prepare standby rockets to hit U.S. targets.

In a meeting with military leaders early Friday, Kim "said he has judged the time has come to settle accounts with the U.S. imperialists in view of the prevailing situation," KCNA reported.

The rockets are aimed at U.S. targets, including military bases in the Pacific and in South Korea, it said.

"If they make a reckless provocation with huge strategic forces, (we) should mercilessly strike the U.S. mainland, their stronghold, their military bases in the operational theaters in the Pacific, including Hawaii and Guam, and those in South Korea," the report said.

Photos: Photos: Militaries and Korean tensions Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – Emergency service personnel wearing chemical protective clothing participate in an anti-chemical warfare exercise on Tuesday, April 16 in Seoul. Tensions remain high in the Korean Peninsula in the wake of North Korea's recent nuclear threats and provocations. A Pentagon intelligence assessment suggests the North may have the ability to deliver a nuclear weapon with a ballistic missile, though the reliability is believed to be "low." Hide Caption 1 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean marines arrive on the island of Yeonpyeong near the disputed waters of the Yellow Sea on Friday, April 12. Hide Caption 2 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – A Japanese soldier is on alert as Patriot Advanced Capability-3 missile launchers are deployed at the Defense Ministry in Tokyo on Wednesday, April 10. Hide Caption 3 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers sit in a truck at the Inter-Korean transit office on Tuesday, April 9, in Paju, South Korea. Hide Caption 4 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers participate in an artillery drill as part of the Foal Eagle joint military exercise by U.S. and South Korean forces near the Demilitarized Zone in Goseong on April 9. Hide Caption 5 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – U.S. soldiers are at a military training field in Yeoncheon, South Korea, on April 9. Hide Caption 6 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers with K-55 self-propelled Howitzers stage at a military training field in the border city of Paju on Friday, April 5, as tensions continue to mount on the Korean peninsula. Hide Caption 7 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers man a cannon at a military training field in Paju on April 5. Hide Caption 8 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers stand guard at a sentry post at the border with North Korea in the Demilitarized Zone near Imjingak, South Korea, on April 5. Hide Caption 9 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – A U.S. Army Patriot missile battery is visible at the U.S. Osan Air Base in South Korea on Friday, April 5. Hide Caption 10 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – The U.S. Navy is moving a sea-based radar platform, like the one seen in this 2006 file photo, closer to the North Korean coast to monitor that country's military moves, including possible new missile launches, a Defense Department official said Monday, April 1. Hide Caption 11 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean marines man K-55 self-propelled Howitzers at a military training field in the border city of Paju on Monday, April 1. Park Geun-hye, South Korea's new president, promised a strong military response to any North Korean provocation after North Korea announced that the two countries were in a state of war. Hide Caption 12 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean anti-aircraft armored vehicles move across a temporary bridge during a river crossing drill in Hwacheon near the North Korean border on Monday, April 1. Hide Caption 13 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers ride on a military truck in Paju on Friday, March 29. Hide Caption 14 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – The United States said Thursday, March 28, that it flew stealth bombers over South Korea to participate in annual military exercises amid spiking tensions with North Korea. Pictured, a B-2 Spirit stealth bomber flies over South Korea's western port city of Pyeongtaek. Hide Caption 15 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers gather at the foot of a mountain near a military drill field in the border city of Paju on Wednesday, March 27. Hide Caption 16 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – Armed South Korean soldiers walk on a road near a military drill field in Paju on March 27. Hide Caption 17 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers ride in a military truck in Paju on March 27. Hide Caption 18 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – A B-52 bomber flies over the wire-topped fence of a U.S. air base in Osan, South Korea, on Tuesday, March 19. Hide Caption 19 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers take part in a drill to guard the building of a state-run telecom company in Seoul against potential guerrilla attacks on Thursday, March 14. Hide Caption 20 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean army soldiers jump off a military truck during a drill outside a U.S. airbase in Pyeongtaek as part of annual joint exercises with the United States on March 14. Hide Caption 21 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean Marines operate K-55 self-propelled howitzers on the western island of Ganghwa near the disputed maritime frontier with North Korea on Wednesday, March 13. Hide Caption 22 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean soldiers stand guard as a North Korean soldier, far center, looks on at the truce village of Panmunjom in the demilitarized zone dividing the two Koreas on March 13. Hide Caption 23 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – South Korean marines patrol on the South Korea-controlled island of Yeonpyeong near the disputed waters of the Yellow Sea on Tuesday, March 12. Hide Caption 24 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – In this Navy handout image taken on March 5, Lt. j.g. Matthew Harmon serves as helm safety officer aboard the guided-missile destroyer USS McCampbell during a replenishment at sea, part of Foal Eagle 2013, the joint exercises between the United States and South Korea. Hide Caption 25 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – Fire Controlman 2nd Class Jason Titcombe, left, hands Fire Controlman 2nd Class Joshua Clements ordnance aboard the destroyer USS Lassen in this Navy handout photo taken on March 5. Hide Caption 26 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – U.S. Navy Boatswain's Mate 3rd Class Brittany Chiles signals to an SH-60B Seahawk helicopter as it lands on the flight deck of the destroyer USS McCampbell on March 4 in the Pacific Ocean, in this Navy handout photo. Hide Caption 27 of 28 Photos: Photos: Militaries and Korean tensions Militaries and Korean tensions – This March 17 Navy handout image shows the destroyer USS John S. McCain, front; the Republic of Korea Navy destroyer ROKS Seoae-Yu-Seong-Ryong, center; and the destroyer USS McCampbell moving into formation in the waters off the Korean Peninsula during exercise Foal Eagle 2013. 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North Korean state media carried a photo of Kim meeting with military officials Friday. In the photo, the young leader is seated, leafing through documents with four uniformed officers standing around him.

On the wall behind them, a map titled "Plan for the strategic forces to target mainland U.S." appears to show straight lines stretching across the Pacific to points on the continental United States.

South Korea and the United States are "monitoring any movements of North Korea's short, middle and middle- to long-range missiles," South Korean Defense Ministry Spokesman Kim Min-seok said Friday.

U.S. official: We're 'committed ... to peace,' unlike N. Korea

U.S. officials have said they're concerned about the torrent of threats coming out of Pyongyang in recent weeks.

"I think their very provocative actions and belligerent tone, it has ratcheted up the danger, and we have to understand that reality," Defense Secretary Chuck Hagel said Thursday.

Some observers have suggested that Washington is adding to tensions in the region by drawing attention to its displays of military strength on North Korea's doorstep, such as the flights by the B-2 stealth bombers.

Hagel argued against that assertion.

"We, the United States and South Korea, have not been involved in provocating anything," he said. "We, over the years, have been engaged with South Korea on joint exercises. The B-2 flight was part of that."

Washington and its allies "are committed to a pathway to peace," Hagel said. "And the North Koreans seem to be headed in a different direction here."

Amid the uneasy situation, China, a key North Korean ally that expressed frustration about Pyongyang's latest nuclear test, also called for calm.

"We hope relevant parties can work together to turn around the tense situation in the region," Foreign Ministry Spokesman Hong Lei said Friday, describing peace and stability on the Korean Peninsula as "a joint responsibility."

Behind North Korea's heated words about missile strikes, one analyst said, there might not be much mettle.

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"The fact is that despite the bombast, and unless there has been a miraculous turnaround among North Korea's strategic forces, there is little to no chance that it could successfully land a missile on Guam, Hawaii or anywhere else outside the Korean Peninsula that U.S. forces may be stationed," James Hardy, Asia-Pacific editor of IHS Jane's Defense Weekly, wrote in an opinion column published Thursday on CNN.com

Tensions have been rising for months

Tensions escalated on the Korean Peninsula after the North carried out a long-range rocket launch in December and an underground nuclear test last month, prompting the U.N. Security Council to step up sanctions on the secretive government.

Pyongyang has expressed fury about the sanctions and the annual U.S.-South Korean military exercises, due to continue until the end of April.

The deteriorating relations have killed hopes of reviving multilateral talks over North Korea's nuclear program for the foreseeable future. Indeed, Pyongyang has declared that the subject is no longer up for discussion.

The recent saber-rattling from Pyongyang has included threats of pre-emptive nuclear strikes against the United States and South Korea.

Most observers say North Korea is still years away from having the technology to deliver a nuclear warhead on a missile, but it does have plenty of conventional military firepower, including medium-range ballistic missiles that can carry high explosives for hundreds of miles.

North Korea has gone through cycles of "provocative behavior" for decades, Pentagon spokesman George Little said Thursday.

"And we have to deal with them. We have to be sober, calm, cool, collected about these periods. That's what we're doing right now," he said. "And we are assuring our South Korean allies day to day that we stand with them in the face of these provocations."