North Korea threatens nuclear annihilation, fires ballistic missiles into the sea in a show of defiance, tests a nuclear bomb and launches a long-range rocket into space as South Korea and the United States stage huge military drills.

A full-blown crisis, right?

Maybe not. Or, at least, not yet.

Things change very quickly on the Korean Peninsula, where a single miscalculation could set off two bitter rivals that face each other across the world's most heavily armed border. But, so far, the current state of affairs is not even close to the past standoffs between the Koreas.

South Koreans, as they usually do, are mostly ignoring the threats, and there's a feeling among many that this is just another fairly standard development in the long, complex rivalry between Pyongyang and U.S.-backed Seoul.

With the caveat that's always needed when talking about North Korea — that is, that no outsider, really, can glean the inner workings of authoritarian, guarded Pyongyang — here's a brief explanation of what's going on:

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WHY IS NORTH KOREA DOING THIS?

Some outsiders think of North Korea and its young leader, Kim Jong Un, as crazy and unpredictable. But although it is very difficult to read a country that applies huge constraints on the media, its citizens and foreign visitors, and locks down most information on government workings, many outside analysts believe Pyongyang is, in large part, actually very careful in its calculations.

In this case, North Korea is doing several things at once.

It is expressing its extreme anger over recent "hostile" U.N. sanctions over the nuclear test and rocket launch, and over decades of annual U.S.-South Korean military drills — this year's version is described as the biggest ever.

Pyongyang, poor but proud, surrounded by regional powerhouses, calls the war games a carefully rehearsed preparation for a northward invasion by two countries that want to topple its leadership. The North is also believed to resent having to respond to the drills with costly exercises of its own, taking its troops away from much-needed work on farms and infrastructure projects.

North Korea must also show strength confronting a new, much harder-line stance in Seoul.

Conservative South Korean President Park Geun-hye has responded to the nuclear test and rocket launch by shutting down the last major point of inter-Korean cooperation, a jointly run factory park in the North. She has also talked openly about the uber-sensitive subject of "regime collapse" in Pyongyang and ordered unilateral sanctions against the North.

North Korea is also trying to give its people a good show.

Ahead of a once-in-a-generation party congress in May, Kim needs to give the impression that he is leading a strong, defiant country that will never bow to outside pressure.

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HOW DOES THIS COMPARE TO PAST CRISES?

So far, it's not even close to rivaling the kinds of face-offs the Koreas have become infamous for.

South Koreans, never likely to panic over even the harshest North Korean threats, are paying much more attention to the fate of South Korean baseball players in the U.S. major leagues, for instance.

This has not always been the case.

In 1968, dozens of North Korean commandos were killed within a few kilometers of the presidential mansion in Seoul during a mission to assassinate the South Korean dictator, father of the current president. In 1976, North Koreans ax-murdered two American officers in the Demilitarized Zone between the countries, prompting a furious Washington to send nuclear-capable B-52 bombers flying toward the North before veering away. In 1994 and again in the early 2000s, nuclear crises seemed at times in danger of prompting armed conflict. Just five years ago, 50 South Koreans were killed in two separate attacks blamed on the North.

If anything, this round may resemble the early stages of a confrontation that happened just two years ago.

Young Kim Jong Un, furious about U.N. sanctions over another nuclear test-rocket launch combination, embarked on a weeks-long torrent of belligerent rhetoric. The North threatened to attack specific targets in South Korea, U.S. bases in the Pacific, even the mainland United States; declared the armistice ending the 1950-53 Korean War null and void; said it was restarting its nuclear fuel reactor; and closed down the jointly run industrial park. The United States responded by staging flyovers of South Korea of nuclear-capable bombers.

Then the war drills ended in the South, the fiery rhetoric from the North eased and then died, the factory park reopened, talk of reconciliation began again — and the animosity began to dip.

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WHAT NEXT?

The realms of media and academia are littered with failed predictions about North Korea's future.

The country's demise, for instance, has been predicted regularly since the end of fighting in the Korean War, in 1953. North Korea couldn't, it was said, survive the death of the country's founder, Kim Il Sung, in 1994, and then the death of his son, Kim Jong Il, and rise of the current young, relatively unexperienced Kim, in 2011.

That said, some analysts think Pyongyang could keep up its stream of threatening rhetoric, stage occasional missile firings to show its anger, even do another nuclear test or rocket launch, at least until the U.S.-South Korean war games stop at the end of April and the North Korean party congress is staged in May.

In the past, North Korea has followed periods of conflict by offering talks meant to win aid.

Seoul and Washington have seen all this before, and know in theory how to respond.

The danger comes from the things they can't control. From a change in the above script. From a miscalculation. From an act of genuine fury by the human beings squared off against each other across the land border or the disputed boundary separating them in the Yellow Sea. Or from an accident.

All of these possibilities make even a "routine" crisis on the Korean Peninsula something to keep an eye on.

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Foster Klug is AP's Seoul bureau chief and has covered the Koreas since 2005. Follow him at www.twitter.com/apklug .