Although fears of Pyongyang responding to South Korea's live-fire drills in the Yellow Sea are diminishing this week, the calm might be short-lived. North Korean leader Kim Jong Il may be planning a provocative act far away from the Northern Limit Line, a sea border drawn by the United Nations at the end of the Korean War. Once again, anonymous "observations of possible test preparation activity" are fueling speculation that North Korea will soon test another nuclear device. Maybe it will … but maybe not. Either way, Pyongyang will have succeeded in increasing international nervousness over what it's up to. North Korea views heightened international anxiety as a good thing, something that gives it leverage to move the United States and its allies to abandon their current high-pressure tactics. This time, however, a nuclear test may not achieve what the regime wants.

Media reports about North Korean nuclear or missile test preparations are not always reliable. In May 2005, for example, the New York Times reported "rapid, extensive preparations for a nuclear weapons test, including the construction of a reviewing stand." Nothing happened. And that is by no means the only instance of false alarms.

Even intelligence analysts have trouble accurately predicting a nuclear test because there are few good indicators. Signs of excavation activity, observable on satellite imagery, may indicate tunneling for a nuclear test. Then again, the digging could be unrelated to any nuclear activity. Less ambiguous indicators — such as instrumentation cabling connecting the nuclear device to monitoring equipment — can be concealed or emplaced only shortly before a test.

Kim may have no intention of popping another nuke. But he knows that his country's nuclear test site is closely monitored by the U.S. intelligence community. Any activity there (or at any of his missile test sites, for that matter) is sure to be noted and interpreted as possible test preparation. That's all that's needed to raise policymaker concern.

Kim would hope that the U.S. and South Korea might fear a nuclear test-generated escalation in tensions sufficiently to offer concessions. Such tactics have worked repeatedly in the past, with Washington and Seoul buying their way back to a calmer status quo. Moreover, the regime perceives it has little to lose from trying the gambit again. Previous provocations have often elicited offers of negotiations or concessions. Never have they been met with punishment.

Like a mischievous child threatening to push over Mom's prized vase unless he's given candy, Kim would hope to gain his objective without conducting the test, thus gaining his objective while retaining the threat for future use.

But Kim would also see an upside to proceeding with a test. It would demonstrate his country's nuclear weapons capabilities and help further refine them. Although the first nuclear test in 2006 was a failed fizzle of less than 1 kiloton, the second test in 2009 produced a 4-kiloton yield.

Siegfried Hecker, former head of the United States' Los Alamos nuclear weapons lab, concluded that the second test indicated North Korea can build a simple, Nagasaki-like plutonium bomb with a yield of 20 or so kilotons. A third test might reflect progress in miniaturizing its nuclear weapons for use on missiles.

Recently, North Korea focused international attention on its pursuit of uranium-based weapons, showing Hecker a sophisticated — and previously unknown — uranium enrichment facility containing 2,000 operational centrifuges. A nuclear test would be an equally dramatic reminder of Pyongyang's existing arsenal of plutonium-based nuclear weapons.

Kim would hope that escalating fears of a dual nuclear breakout — an improved plutonium weapons arsenal and accelerated uranium production capability — would drive Washington and Seoul back to the negotiating table — on Pyongyang's terms.

During the last two years, North Korea has used a series of provocations to press for international acceptance as a nuclear weapons state, improved relations with Washington, a peace treaty formally ending the Korean War and reduced U.S. military presence in the region.

But two years of belligerence has not worked as Pyongyang hoped. Indeed, it has backfired. The Obama administration's response has been to adopt a much more forceful policy than originally envisioned and to pursue a stronger package of sanctions. Additional North Korean military attacks on South Korea could even trigger Seoul to respond more harshly.

Kim may soon find himself in the same situation as the boy who cried wolf once too often. A third nuclear test may have much less impact on the world psyche than he imagines. Indeed, it would most likely simply reinforce U.S. and South Korean resolve to pursue sterner measures against a recalcitrant regime. There might even be some cackling that Pyongyang had destroyed more of its limited fissile material.

Bruce Klingner is senior research fellow for Northeast Asia at the Heritage Foundation (heritage.org).