North Korea's nuclear policy today seems based on a simple and clear, but potentially fatally flawed, premise; namely that its all-out effort to develop and possess the ability to put a nuclear warhead on an intercontinental missile and launch it at the United States will somehow ensure the security of the nation and regime. Nothing could be further from the truth! The closer Pyongyang gets to achieving this capability, the greater becomes the cost (to the U.S., South Korea and Japan, and even to China) of allowing it to do this.
For decades now, U.S. and South Korean military forces have been deterred from attacking North Korea not because of any embryonic nuclear weapons capability but because of the destruction that the North's conventionally armed rockets, missiles, and artillery could rain on Seoul. Even though the final outcome has never been in doubt, the costs associated with pursuing a military solution outweighed the costs of tolerating the Kim regime's existence.
But this calculus is changing. The costs associated with continuing to do nothing and thus allowing Pyongyang to fully develop the capability of putting a nuclear weapon on Seoul, Tokyo or the U.S. proper will soon outweigh the costs associated with the use of military force. At that point, the use of force becomes a viable, if not inevitable, option. North Korean threats to launch a pre-emptive nuclear attack against the U.S. or South Korea provide greater justification for such action.