SEOUL, South Korea – North Korea on Monday canceled the armistice agreement that nearly 60 years ago brought a cease-fire to the Korean War, leaving a world of analysts wondering how far the secretive police state will go to show its displeasure with South Korea and its American ally, which still has 28,500 troops based in the South.

The move, reported by the official Rodong Sinmun newspaper, was anticipated – Pyongyang had said last week that it intended to do so in the wake of new U.N. sanctions over its nuclear weapons program. But the ramifications of the development – the papers cited a military spokesman as saying the armistice had been "scrapped completely" – are far from clear.

Pyongyang is infamous for issuing dramatic but empty threats, like turning its enemies into an apocalyptic "sea of fire." The North has also announced on several previous occasions that it was pulling out from the armistice, most recently in 2009.

So on Monday evening, life appeared from the outside to go on as normal in South Korea's sprawling capital, which lies just 31 miles from the North Korean border. Lights twinkled atop skyscrapers, young men wearing hipster glasses waited for buses, and cars zipped across a lacework of urban roadways.

Yet this crisis has a graver cast than previous North Korean bombast. In December, North Korea launched a satellite into outer space, a step seen as an advance in its ballistic missile program. Then last month, the country conducted a successful test of a nuclear weapon.

South Korea said Monday that its calls to a hotline maintained between the two countries went unanswered. Seoul's Ministry for Peninsular Unification said that the North "seems to have disconnected the emergency link," according to South Korea's Yonhap News Agency.

The last time North Korea disconnected the hotline, in 2010, the North killed four South Koreans when it shelled an island and was accused of torpedoing a South Korean naval ship, killing 46 sailors.

But Yonhap also reported that the North had not severed another North-South communication line, this one to a North Korean industrial zone where South Korean companies operate.

South Korea's new minister of unification, Ryoo Kihl-jae, said Monday that despite the current strains, "holding talks is critical."

Yonhap paraphrased Ryoo as saying that "depending on future developments, South Korea can examine ways to offer humanitarian support to the North." Still, he noted, "It is hard to discuss other matters when the North is making military threats."

North Korea has in the past week threatened to wage war against both the United States and South Korea.

Judging the seriousness of those words is complicated by the clutter of past threats that have gone unfulfilled and the fact that North Korea is among the most opaque and unpredictable nations in the world.

The nation is led by Kim Jong Un, a man thought to be 30 years old who took over after his father, Kim Jong Il, died in December 2011. In the days leading up to its talk of obliterating enemies near and far, North Korea hosted former American basketball star Dennis Rodman and three members of the Harlem Globetrotters.

Nonetheless, a state news agency in Pyongyang on Thursday cited a North Korean Foreign Ministry spokesman as saying the nation would "exercise the right to a pre-emptive nuclear attack to destroy the strongholds of the aggressors."

The rhetoric from the North has been fueled by its anger over both recent U.N. sanctions and a combined military exercise by U.S. and South Korean forces that began Monday and is scheduled to last until March 21.

Still, there has been a notable ratcheting-up of tension since the December rocket launching that the United States and others say marked a significant advance in North Korean missile technology.

Meanwhile, a statement by the North Korean military last week, carried by state press, threatened a nuclear exchange.

"The U.S. imperialists seek to attack the DPRK even with nuclear weapons," the statement said, using the initials for North Korea's official name, the Democratic People's Republic of Korea. Pyongyang, the statement threatened, "will counter them with a diversified precision nuclear strike."

The North is not thought to currently have the capacity to launch such an attack on the continental United States, but its neighbors to the south were not pleased.

The South Korean military responded by "warning it would strike back at the North and destroy its 'command leadership,' if provoked by Pyongyang," according to Yonhap.

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