North Korea is at the center of one of the most sophisticated surveillance stakeouts in the history of the world. U2 spy planes photograph it daily. Electronic equipment on planes and ships and bases across Asia monitor its radio and telephone communications. Satellites orbiting in space can pinpoint a broken-down North Korean military truck and count the number of soldiers working on it.

But in the end, one of the world's most menacing little empires is still unknown. It might have a nuclear bomb or two, it might not. It might be crazy enough to use them, it might not. Despite all the high-tech clues and relentless scrutiny, nobody knows why President Kim Jong Il runs his country like Evel Knievel driving a motorcycle at 90 mph toward Dead Man's Curve on a rainy night.

That North Korea knowledge gap grew to be a haunting obsession for us during our four years as The Post's Northeast Asia correspondents, covering Japan and Korea. North Korea is a poor, Dark Ages fortress the size of Pennsylvania sitting in the middle of a huge Neon Asia crackling with e-mail, bullet trains and Starbucks coffeehouses. Against all odds, North Korea still manages to lock itself away from the world and limit what others know about it.

Two million to 3 million North Koreans have died of malnutrition and disease--according to the best estimates of international relief groups--in mountains and villages not a three-hour flight from Tokyo. And we couldn't get in to write about their plight or take pictures--the kind of media coverage that has helped to mobilize the world in response to African famines.

So we began banging on North Korea's door. Via phone, fax and e-mail, we made more than 100 appeals to aid agencies, religious groups, members of Congress, various South Korean, Japanese and European officials and the North Koreans themselves, in an effort to get inside the country. The answer--as it is to almost all foreigners--was always no. North Korea has allowed a string of aid workers and religious groups--and a handful of reporters--inside in recent years, but what they are allowed to see is always restricted.

So with the front door closed to us, we made it our mission to peek in as many windows and cracks as possible.

We visited South Korea more than 50 times. We wandered to remote Paengnyong Island, just nine miles off the North Korean coast, where every high school student learns to shoot a gun, in case North Korea invades again.

We made a dozen trips to this militarized border village of Panmunjom, where goose-stepping North Korean soldiers stare you in the face on this bizarre last stage of the Cold War. We spent time at Observation Post Ouellette, a fortified hilltop bunker 35 yards from North Korea, where American soldiers watch the North Koreans with spy gear so sophisticated it can track a North Korean soldier patrolling in the woods at night a mile away; they see every time he kicks a rock or scratches his head.

We roamed remote stretches of the China-North Korea border, talking to emaciated North Korean children on the dusty streets of Tumen, China. They recounted horrific stories of depravity and hunger that made them flee their homeland despite border guards who shoot to kill. A diplomat told us of seeing one North Korean who had fled but was returned by Chinese soldiers: North Korean troops drove a spike through the defector's hands, attached a chain to it and hauled him away.

We traveled to the Russian Far East to report on North Koreans working as forced labor on Vladivostok construction sites, with their wages sent directly to the government in Pyongyang. We saw the scarred faces and broken arms of a lucky few who managed to escape from primitive wilderness lumber camps in Russia. They described the filthy, freezing conditions there and how their comrades who died from exposure, beatings or sawmill accidents were stacked like cordwood for transport back to North Korea.

This is what became clearer the longer we spent looking into North Korea--talking to generals and admirals, presidents and mud-splattered soldiers, spymasters and spies, defectors, economists, analysts and even a famous fortune-teller, from Beijing to Rangoon to Hong Kong: One of the cruelest regimes ever to rule a nation will carry its cloaked inhumanity into the new millennium.

The irony is painful. The rest of Asia may be wiring up for the Digital Age, but the 20 million people inside North Korea run the risk of being jailed for flipping on a radio that can pick up foreign broadcasts. They do not have enough to eat. They do not have anesthesia for surgery. They are hostages--unable to leave North Korea, unable to speak their mind or to learn of the outside world under penalty of death at the hands of Kim's security thugs.

And the outside world has largely chosen to look aside. For the United States, human rights is a secondary issue in North Korea. In their private moments, U.S. officials agonize over the abuses suffered by North Korea's people. But they do not intend to jeopardize fragile talks on ballistic missile and nuclear arms proliferation by raising emotionally charged human rights questions. The thin strand of dialogue between Pyongyang and Washington can bear only so much weight, they say. Washington has calculated that it's more important to try to disarm Kim than to lecture him about humanity.

When we arrived in Asia in 1995, North Korea seemed like a nation on its knees, brought virtually to collapse by its dying economy and severe food shortages. But today, thanks in considerable part to foreign aid that has included $500 million from the United States and more than $1 billion in current and future investment from South Korea, North Korea is standing taller--still wobbly, but stronger.

But North Korea isn't sending thank-you notes.

Rather, the country has responded to desperately needed foreign food, fuel, fertilizer and a nearly $5 billion nuclear power project (funded mainly by South Korea and Japan) by expanding its ballistic missile program. Last August, North Korea test-fired a missile that soared over Japan. Pyongyang says it was launching a small satellite. It now appears ready to test-fire a long-range missile that may be able to reach Alaska and Hawaii.

And few believe North Korea has abandoned its efforts to build a nuclear bomb: It threatened last week to reverse its 1994 commitment to freeze its nuclear weapons program unless Washington begins to show "good faith" by lifting economic sanctions, which have been in place since 1950.

South Korean President Kim Dae Jung's "sunshine policy" of engaging North Korea with political and economic incentives to encourage better behavior has yielded positive results and won supporters in Washington and even Beijing and Moscow. But sunshine is now entering a "partly cloudy" period.

It has become clear that foreign money has not purchased the hoped-for leverage with Pyongyang.

South Korea's President Kim, in a recent interview with us, argued that aid equals influence, and that by continuing to invest in North Korea, Seoul will be better positioned to try to shape events there. Maybe he is right, and maybe continued aid and patience with North Korea will prove to be the wisest course. But foreign aid has not persuaded North Korea to cease its most threatening behavior, calling into question whether it ever will.

A growing chorus of critics in Seoul and Washington says that perhaps it's time to give North Korea a taste of life without the foreign gravy train, at least in the short term, regardless of whether it launches another missile. Such a shift could have serious consequences; perhaps North Korea would lash out if cornered. That's impossible to predict, given the country's reclusive nature. But policy makers may be left with no other choice than to try a little more stick if North Korea keeps spitting out the carrots it has been offered.

The question may become moot if North Korea launches a new missile despite the warnings from President Clinton and others. If that happens, Japan and the United States will almost certainly freeze further aid, and even the South Korean president will be forced to decide whether his overtures are working.

After reviewing North Korea policy for several months, White House envoy William Perry traveled to North Korea in June to discuss a new era in relations between Pyongyang and Washington. In essence, Perry was offering North Korea a concrete path toward respectability on the world stage and economic recovery, in exchange for North Korea shelving its missile program and nuclear weapons ambitions. There has been no official North Korean response--just a string of hostile actions since Perry departed, further clouding Pyongyang's intentions.

In the Korean War nearly half a century ago, American misreading and miscalculation about North Korea and its communist allies, the Soviet Union and China, added greatly to the death toll, which included nearly 37,000 American troops. Today, the same number of American soldiers remain posted in South Korea. Their lives and those of millions of Koreans on both sides of the demilitarized zone may well rest on Clinton's approach to North Korea, and whether he reads its intentions better than President Truman did.

In Panmunjom, South Korea has spent millions of dollars to build a steel-and-glass "Freedom House." We have roamed its soaring atrium and wide granite stairs, but aside from visits by officials, journalists and tourists who come to gawk at North Korea, Freedom House is closed. Someday it is supposed to be a customs house, a gateway between two neighbors with more normal, healthy relations, a place where the divided families of the Korean Peninsula can reunite. And maybe someday beyond that, it might be a museum in the center of a reunited peninsula.

But for now, just as North Korea remained elusive to us, the potential of Freedom House eludes the people of this divided peninsula. It sits cold and empty, its possibilities distant dreams.

Kevin Sullivan and Mary Jordan have just completed a four-year assignment as The Post's bureau chiefs in Tokyo. They will spend the next year at Stanford University, studying on a John S. Knight fellowship.