North Korea's response to the United Nations resolution demanding that it suspend its ballistic missile program and resume a moratorium on launches was typically belligerent. But like the multiple launch of seven missiles earlier this month, the North Korean vow to continue to fire off its missiles should not be dismissed as mere political theater.

The missile tests were neither a gesture of defiance nor a desperate bid for negotiations. Nor can they be dismissed as the impulsive act of an irrational leader. It was, as Pyongyang itself so succinctly put it, a "military exercise."

The launches are only the latest evidence of a decadeslong effort by Pyongyang to redress the military balance in its favor. For North Korea, missiles are an attempt to compensate for weakness. The communist state has a large but technologically backward army, lacking the air power to compete with the United States and its South Korean ally. Rockets give it the firepower to back an assault on the South and to hold U.S. forces in Japan, the rear base for Korea, at bay.

The late North Korean leader Kim Il Sung set this goal as far back as 1965 when he established an academy to develop missiles and other modern weaponry.

"If war breaks out, the U.S. and Japan will also be involved," he said. "In order to prevent their involvement, we have to be able to produce rockets which fly as far as Japan."

I encountered one crucial tentacle of Kim's program some 14 years ago, in late October of 1992.

A group of 64 Russian rocket scientists, accompanied by their wives and children, were stopped just as they were about to board a flight to North Korea. The scientists were employees of a super-secret facility in the Urals, the V.P. Makeyev Design Bureau, responsible for the development of the Soviet Union's submarine-launched ballistic missiles.

As the bureau chief for the Christian Science Monitor, I pieced the story together later from Russian press accounts and interviews with the scientists and others. A middleman with apparent official backing had offered the bureau, starving for orders and left adrift by the sudden end of the Cold War, work in North Korea.

Scientists who were making the equivalent of $15 a month jumped at offers of up to $4,000 a month to help a former Soviet ally. In the spring, a group of 10 scientists had gone for an initial foray. The Koreans, one of the scientists told me, initially never directly asked about nuclear warheads or missile designs. They claimed only to be interested in rocket science.

The Russians came home that fall and signed up dozens of their comrades as recruits. But the project was not officially sanctioned, and the KGB held them outside of Moscow for two months while the broker tried to re-negotiate their departure. Russian officials later described the North Koreans' aim, without mentioning them by name, as an attempt to build "combat missile complexes that could carry nuclear weapons."

North Korea began with copies of Soviet short-range Scud missiles and moved on to medium-range "Nodong" missiles, but they lacked the range and accuracy to meet Kim's target. A decade after the airport incident, in 2003, credible reports emerged that the North Koreans were deploying a new, far more accurate missile based on the Soviet SS-N-6, a submarine-launched rocket developed by Makeyev in the 1960s. The Nodong-2, as some labeled it, could reach all U.S. bases in Japan and possibly even to Guam.

In the 1990s, the North Koreans developed a long-range missile, potentially reaching U.S. territory, to lend credence to claims they could deter a pre-emptive strike on their nuclear or missile facilities. Some experts believe the Nodong-2 also functions as the second stage of this missile. American intelligence officials believe an otherwise inexplicable leap in missile technology was thanks to the help of Russian scientists.

Still the self-imposed missile test moratorium that Pyongyang agreed to in 1999 made it difficult to move ahead. Late last year, according to a recent Wall Street Journal story, the North Koreans delivered a dozen Nodong-2 missiles to Iran, a close collaborator on missiles since the 1980s. Unconfirmed reports from Germany say Iran tested the missile in January.

The Nodong-2 may have been tested this month, one of the six short- and medium-range missiles set off in a wave or as a stage of the long-range missile. Data from the launch is not yet conclusive, according to U.S. and South Korean officials. Despite the failure of the long-range attempt, it may be more significant that Pyongyang carried out the first successful launch of a Nodong since 1993 and a nighttime barrage of Scuds and Nodongs.

The display of diplomatic unity at the United Nations may give Pyongyang pause. But the relentless nature of North Korea's pursuit of its ballistic missile strength suggests that this is not a bargaining chip that will be readily traded away.

BEIJING - A message from President Bush to North Korean leader Kim Jong Il will be delivered Monday in Pyongyang -- via two Chinese officials. Beijing now meets quarterly with Mr. Kim, the most contact the unpredictable North has with any outside party. Whether Vice Foreign Minister Wu Dawei and Vice Premier Hui Liangyu will surprise Kim Jong Il and exert real pressure is unclear.

With an international diplomatic effort under way a week after North Korea tested seven missiles, China has proposed informal six-party talks as a way to move the process along.

That is less than the US hoped for from China. But since China insists that it will veto any UN sanctions against the North, the US will accept such talks, according to envoy Christopher Hill.

All told, Beijing would appear key to shaping how the world deals with the defiant Kim. Yet from the moment Kim launched his missiles, China has denied it has clout; it politely insists that the US has the central role.

Since 2003, China has embarked on a historic effort to prop up and aid North Korea -- a state it had the frostiest relations with for more a decade. Now, $2 billion in aid gives Beijing unprecedented access -- something China is reluctant to squander, to "mix aid and diplomacy," as a Chinese scholar here puts it.

"China's influence on North Korea is more than it is willing to admit, but far less than outsiders tend to believe," says a recent report by the Seoul branch of the International Crisis Group.

To outsiders, it appears that a rising China -- running a lifeline of energy and food to its poor comrade - ought to have clout in Korea, as it holds more carrots and sticks than anyone. It seems axiomatic that Beijing can simply apply ancient Chinese wisdom and modern Chinese might to stop Kim's nuclear ambition. Both states are communist, wear green and red uniforms, fought the US together, and share borders and history. China is the only country with easy access, as well as trade and tourism, to the North.

"China does have leverage, but it is afraid it may overplay its hand," says Joseph Cheng, head of the political science department at City University in Hong Kong.

Since Kim Jong Il's July 4 missile shots, voices from Sandy Berger, President Clinton's security adviser, to John Bolton, US ambassador to the UN, have argued that "China is the key" to dealing with North Korean belligerence. It has become nearly a mantra in Washington. Twelve months ago, it was an article of faith in senior White House circles, misplaced or not, that China would deliver a deal with Kim to dismantle his nuclear program. Yet this did not happen.

Instead, with the US preoccupied in Iraq, China embarked on a quiet policy of self-interest: to strengthen North Korea. That policy helps to maintain the North as a "buffer state" between China and South Korea.

China does not want the North to collapse, and for US troops to fill the vacuum and appear on its northeast border. China has hosted Kim, and moved relations away from a bad patch in the 1990s, during the North's epic famine, when China asked for cash payments for food instead of barter.

In the past two years, Chinese officials have told Kim that he can reform his state along socialist lines just as China did. China has indicated it will help with economic aid, while he retains complete political control. To now castigate Kim could wreck that formula, sources say.

In the larger sense, Kim's launch of missiles, most of which could hit long-time nemesis Japan or US bases in East Asia, puts China in the position of choosing between its North Korean comrade and an evolving consensus in the international community. So far, China has tried to please both sides.

"I'm concerned that China isn't recognizing how serious this issue is," says Zhang Liangui, head of foreign studies at the Central Party School in Beijing, in a rare dissent. "China is taking a rigid position. Yet we have long said that if China wants to be viewed as a responsible superpower, it must not be isolated in the international community."

Adding to Beijing's problems is an unresolved ideological struggle in China -- where "neo-orthodox" hard-liners who maintain contact with North Korea want China to support its revolutionary posture. There is also genuine puzzlement in Beijing over how to deal with Kim, whose founder-father, Kim Il Sung, reputedly warned him many times that China would attempt to take over his regime one day.

"I hear often that China is the key, which involves a set of policy steps Beijing can take that will bring about the outcome the allies want," says Russell Leigh Moses of People's University. "But I have yet to see anyone show how if China does X, Pyongyang will do Y."

The White House seems to have abandoned its 2003 optimism that China will harness Kim. China may agree that a nuclear peninsula and a regime that test-fires rockets is not desirable. But it isn't clear on how to force Kim to open his highly controlled state and allow international inspectors to flood in, witness his system of gulags, and bring in potentially subversive material -- all to dismantle a nuclear program he's cherished for decades. The White House seems to understand this.

Scott Snyder of Stanford University argues the US is using the same strategy that it used with China in closing down Kim's accounts in Macau. China was forced to choose between the international regulatory authority, or North Korean money-laundering behavior.

Sunday, Undersecretary of State Nicholas Burns argued on FOX News Sunday that "It's time for China to exert its influence that it does have on North Korea." Also on Sunday programs, US and Japanese officials claimed they might have the votes to support a Japan-backed resolution for sanctions against the North.

WASHINGTON - Despite its threat of severe consequences, the Bush administration has little leverage to use on North Korea to keep it from testing a long-range missile and few ways to punish the nuclear-armed nation if it proceeds.

The United States has no diplomatic or economic ties with North Korea, the rudimentary U.S. missile-defense system is untested in real-world conditions and Pyongyang is regarded as having a right to test missiles, making any American attack to forestall a launch an act of war with potentially explosive consequences.

"The United States could try to shoot down the rocket, but good luck,'' said Wonhyuk Lim of the Brookings Institution, a policy-research organization in Washington.

The dearth of options illustrates the limits of the administration's pre-emption strategy and its need to rely on the cooperation of others -- especially given the strains on the U.S. military from Iraq and Afghanistan -- to contain threats.

Washington hopes that the world's only Stalinist regime will heed demands by the United States, South Korea, Japan, Russia and China to uphold a self-imposed 1999 moratorium on missile tests and rejoin talks on curbing its nuclear program in return for security guarantees and economic and political benefits.

At the same time, the administration is reviewing its options should the Kim Jong Il regime test-fire what U.S. officials describe as a multi-stage Taepodong-2 missile, thought to be capable of reaching Alaska.

"The launch of a missile would be a provocation,'' Assistant Secretary of Defense Peter Rodman said Thursday during a House Armed Services Committee hearing. "If such a launch took place, we would seek to impose some cost on North Korea.''

Rodman declined to say what Washington would do. Experts said that even the imposition of sanctions by the United States would be largely symbolic.

They think that North Korea would not have readied the missile for flight unless it had decided it could live with the consequences.

"It probably means they are not worried about the American reaction,'' said Daniel C. Sneider of Stanford University's Shorenstein Asia-Pacific Research Center. "There is nothing that the United States can do to them.''

The United States has no diplomatic relations or financial assistance it can threaten to cut, and it suspended contributions to international food aid for North Korea last year.

The administration has moved against Pyongyang by trying to halt its missile sales to other countries, its alleged international narcotics trafficking, and its alleged counterfeiting of U.S. currency, cigarettes and over-the-counter drugs.

Under American pressure, banking regulators in February froze North Korean accounts at the Banco Delta Asia, a Macao bank that the U.S. Treasury Department accused of laundering North Korea's ill-gotten gains.

Other banks, anxious to avoid American scrutiny, reportedly have curtailed business with North Korea.

David L. Asher, a former Treasury Department official who oversaw the crackdown on North Korea's alleged illicit dealings, said the United States could respond to a test with an intensified campaign against Pyongyang's alleged international criminal activities that would hurt the ruling elite.

"Do not underestimate the impact of the financial pressure we could put on them,'' said Asher, a scholar with the Institute for Defense Analyses, a policy-research organization.

Washington is counting on Japan, which also is threatened by Pyongyang's nuclear arms and missile programs, to react to a launch by closing ports to North Korean ships and shutting off remittances by ethnic Koreans to relatives in North Korea. But those measures are expected to have limited impact.

A North Korean missile test in 1998 prompted Japan to boost missile-defense cooperation with the United States, and experts said a new launch probably would prompt Washington and Tokyo to forge even closer military ties.

The only nations that could tighten the screws significantly are China and South Korea, North Korea's main foreign trading partners and aid donors.

But while Seoul and Beijing would be outraged, because a missile test would effectively kill hopes of restarting talks on containing North Korea's nuclear arms program, they are unlikely to take any step that could rock Pyongyang.

Both are anxious to avoid destabilizing their neighbor of 26 million people. China doesn't want to be overwhelmed by North Korean refugees, and South Korea would be unable to bear the economic and social costs of sudden reunification.

They also fear that Kim's government could lash out with its million-member army against the South, igniting a conflict that would drag in the United States and devastate the Asian-Pacific economy.

"China and South Korea fear instability more than they fear a nuclear North Korea,'' said Marcus Noland, an expert at the Economic Policy Institute.

Moreover, Beijing probably would be unwilling to jeopardize the budding commercial ties it has been pursuing with North Korea.

"China opposes sanctions on North Korea because it believes they would lead to instability, would not dislodge the regime but would damage the nascent process of market reforms and harm the most vulnerable,'' said a February report by the International Crisis Group, a conflict-prevention organization.

South Korea has been pursuing a policy of economic engagement and political exchanges with North Korea.

The United States has been consulting with members of the U.N. Security Council on a response to a North Korean test. But North Korea has the right under international law to test-fire missiles, making it tough for the United States to win more than words of chastisement of North Korea from the council.

Japanese politics have long been driven by patronage and pork. Prime Minister Junichiro Koizumi has managed to add personality to the mix. Issues, when they mattered at all, were deeply domestic -- the last election, for example, focused on deregulation of the postal savings system.

So it is a bit of a shock to find Japan embroiled in a political struggle with foreign policy topping the agenda. The contest to succeed Koizumi has become a surrogate battleground for a debate over how to repair Japan's tattered relations with its Asian neighbors, China and South Korea.

Put simply, this war of ideas has two schools -- Conservative Realists and Assertive Nationalists.

The Realists fear that Japan has become dangerously isolated from Asia, its influence waning to the benefit of China. Constant tensions with China and South Korea put Japans economic recovery at risk, they worry. The Realists blame Koizumi for his provocative visits to the Yasukuni shrine to Japan's war dead and worry he tilts too far in his embrace of Bush and his policies in places such as Iraq and Iran.

The Nationalists see China as the principal national security threat to Japan. Their priority is to strengthen the alliance with the U.S., even at the cost of ties to Asia. They believe it is crucial to stand up to what is seen as Chinese bullying, symbolized by Beijing demanding that the Yasukuni visits stop as a price for high-level contacts.

This debate harkens back to the Meiji era and Japan's emergence as a great power. But the tortured history that ensued has left a clear legacy -- both camps accept the U.S. alliance as the foundation of Japanese security. The issue now is one of balance and relative independence in the formation of Japanese policy.

Each camp has a champion in the unofficial campaign for the September vote to replace Koizumi as president of the conservative Liberal Democratic Party -- a post that carries with it the premiership. Chief Cabinet Secretary Shinzo Abe, the frontrunner and Koizumi's preferred successor, represents the Nationalists. Yasuo Fukuda, who served as chief cabinet secretary for four years, until 2005, carries the Realist flag into battle.

Abe and Fukuda are cast from almost identical molds. Both are veteran politicians, scions of famous political families, even members of the same faction within the party. Yet they offer remarkably contrasting positions on Japan's diplomatic path in Asia and, less visibly, on how to manage relations with the U.S.

Abe, at age 51, is considered a representative of the younger generation. Like Koizumi, he has personal appeal, at ease on television and able to speak directly and emotively. Abe is the son of a former foreign minister and grandson of former Premier Nobusuke Kishi, a towering figure in post-war conservative politics.

Fukuda, who turns 70 in July, is an old-style Japanese politician, more comfortable working behind closed doors than in front of the TV cameras. "Fukuda is cool, rational, calculating, practical, nonideological and noncommunicative," comments William Breer, a former senior U.S. diplomat in Japan. Fukuda, too, is the son of a major conservative leader, former Premier Takeo Fukuda.

Abe is the front-runner, scoring well in polls and among party members. But Fukuda's star has risen in recent months, tied largely to the rise of tensions with China.

"Fukuda looks more mature, serious and experienced," says Breer. "People want better relations with China, though not at any cost. Fukuda can probably deliver that. Abe may not."

The starkest gap between the two men is over Yasukuni. Fukuda led an effort five years ago to create a secular memorial that would allow a prime minister to honor the war dead while avoiding the issue of the 14 Class A war criminals enshrined at Yasukuni and the unabashed lack of remorse over the war displayed at the shrine's museum.

Fukuda decried the defiant rhetoric in Japan surrounding the shrine, which has become a symbol of defying Chinese pressure. "Discussions in Japan have escalated too far," he said in a speech in late May. "Voices raised here reach China and South Korea, creating a vicious cycle."

Abe, like Koizumi, sees China's interference on Yasukuni as the problem.

"China's diplomacy is high-handed," Abe said recently. "If we permit China to engage in such diplomacy, China will also take a similar attitude on other issues."

But recently Abe pointedly avoided directly answering the question of whether he would continue the shrine visits. That has led some to speculate that Abe may want to find a way out of this cul-de-sac.

The Japanese public, according to recent polls, is evenly divided on the question of whether the next prime minister should visit Yasukuni. They overwhelmingly support the goal of improving relations with Japan's Asian neighbors, but a majority is also sympathetic to Abe's stance against Chinese pressure on Yasukuni.

Beyond Yasukuni, the two men offer contrasting visions of Japan's relationship to Asia and response to growing regional integration.

Fukuda points to the example of the "Fukuda Doctrine," a 1977 initiative by his father that responded to rising anti-Japanese sentiment by declaring that Japan would not become a military power and would try to build relations in the region as an equal partner.

In a series of recent speeches, Fukuda advocated integration of the region through an economic partnership agreement and called on Japan, China, and South Korea to cooperate toward this end. He visited South Korea in March along with former Prime Minister Yasuhiro Nakasone and met with the South Korean president.

Abe, in contrast, echoes the Bush administration in calling for a strategic dialogue with India, Australia, and other democracies in Asia, as well as the U.S., unifying on the basis of common values -- widely interpreted as a thinly disguised attempt to counter China's rise.

They differ on other issues. Abe is a hardliner on North Korea, while Fukuda has pushed for negotiations. Abe puts revision of Japan'a antiwar constitution at the top of his priority list. Fukuda warns about hasty steps that would alarm Japan's neighbors.

When it comes to managing the U.S. alliance, the choice is subtle. Both have strong ties to the Bush administration. Fukuda played a key role in forging the Japanese rapid response to the September 11 attacks, including the decision to send ships to support the war in Afghanistan. Both supported the dispatch of peacekeeping troops to Iraq.

"Fukuda, however, might be a little more honest in evaluating U.S. foreign policies," suggests Breer. "He might not be as pliable as Koizumi."

Abe remains the favorite to win, particularly among LDP members. But Fukuda's fortunes may have been aided by the emergence of Ichiro Ozawa as leader of the main opposition party. Ozawa, a remarkable political operator and former LDP leader, believes in issue-based politics. He visited China this week and met with Hu Jintao, which suits his clear Realist agenda.

Other events could shape the fight. Koizumi has signaled his desire to visit Yasukuni on August 15, the anniversary of Japan'a surrender. Some analysts suggest that could strengthen Fukuda's appeal. Alternately, the North Korean test missile launches could consolidate Abe's bid for power.

Whatever the outcome, this succession fight will likely mark a turning point for Japan. It could slow -- or perhaps accelerate -- the slippage toward Sino-Japanese tensions. And it will mark the re-emergence of a Japan that looks outward. It is time for the rest of the world to pay attention to Japanese politics.

North Korea is poised to flight test a ballistic missile that may have intercontinental range -- an action the Bush administration declares would be provocative. Others have called for sanctions if the flight test occurs, the use of U.S. ballistic-missile defenses to intercept the missile in flight or a pre-emptive attack against the missile-launch site. But is this missile test a red line that, if crossed, seriously threatens U.S. security and, hence, warrants strong action? The simple answer is "No."

In thinking about this test, one must not lose sight of two paramount goals: rolling back North Korea's nuclear weapons program and the eventual peaceful reunification of North and South Korea. Ballistic missiles constitute a serious threat to the U.S. homeland only when armed with nuclear warheads and they are only one delivery means for such weapons. In this sense, ballistic missiles are of secondary concern. By most estimates, North Korea has sufficient nuclear material for a few nuclear explosive devices, but whether they can design a nuclear weapon that satisfies the size, weight and delivery constraints associated with intercontinental-range ballistic missiles is far from obvious.

If North Korea tests a three-stage version of the Taepodong-2 missile, it will likely attempt to put a satellite into orbit, just as it did in 1998 when it failed to place a satellite into orbit with the smaller Taepodong-1 missile. North Korea has a sovereign right to launch satellites, or to test ballistic missiles for that matter. International protocol requires launch notification and restrictions on air and marine traffic for reasons of range safety -- steps North Korea failed to take in 1998 -- but no international agreement bars this test. True, North Korea agreed to a unilateral moratorium on ballistic missile flight tests in 1999, pending further talks with the United States regarding North Korea's missile program, but the Bush administration refused to join these talks. North Korea leader Kim Jong Il reaffirmed this flight test moratorium in the 2002 Pyongyang Declaration signed with Japan, but this document is not a legally binding commitment.

If successful, this flight test would demonstrate that North Korea can produce rockets large enough to carry payloads intercontinental distances. However, this does not translate into an immediate threat because North Korea has not demonstrated that it can build a nuclear warhead that is small enough to fit on top of a Taepodong-2 missile and that can survive re-entry into the atmosphere after flying intercontinental distances.

Given vastly superior U.S. conventional and nuclear forces, deterrence should dissuade North Korea from ever using such missiles, except for saber rattling, or worse selling nuclear weapons or nuclear material abroad (this is a serious red line). Kim Jong Il may be a ruthless totalitarian leader, with little regard for the welfare of his people, but he is not suicidal.

More important, these missiles would be highly vulnerable to pre-emptive attack in the midst of a crisis, which is when pre-emption makes sense, because these missiles are large and easy to detect, they are not mobile, and they take many hours, if not days, to erect in a vertical position and fuel -- precisely the activity that generated this concern.

On the other hand, U.S. sanctions against North Korea in the wake of a test flight could backfire. They would likely cause rifts with other friendly parties to the Six Party talks aimed at eliminating North Korea's nuclear weapons, especially China. U.S. national missile defenses may not be within range, depending on the flight trajectory, to intercept this flight test. If this unproven U.S. missile defense were to fail and North Korea's flight test succeed, the Bush administration would be embarrassed, and Kim Jong Il triumphant. And, pre-emptive attack against the test facility would be a unilateral act of war at a time when U.S. unilateralism has hurt more than helped U.S. vital interests. South Korea would adamantly oppose such adventurism because Seoul is vulnerable to retribution, being within artillery range of the Demilitarized Zone.

So, what should the United States do on the eve of this flight test? Nothing, beyond expressing its dismay that North Korea appears to favor conflict over cooperation.

A Taepodong-2 flight test allows the United States to learn more about this missile than North Korea, given the concentration of technical intelligence assets in the area, which would help resolve the question of whether this missile, in fact, constitutes a serious threat to the U.S. homeland. In addition, such a test would isolate North Korea further and reinvigorate the Six Party Talks by encouraging South Korea, China, Japan, Russia and the United States to overcome their differences and create a united front to persuade North Korea to renounce its nuclear weapon program, which is the real threat.

Stepping back, U.S. leaders should see that North Korea is a mouse and the United States the elephant. Contrary to popular mythology, elephants are not, and should not be, afraid of mice.

North Korean technicians are reportedly in the final stages of fueling a long-range ballistic missile that some experts estimate can deliver a deadly payload to the United States. The last time North Korea tested such a missile, in 1998, it sent a shock wave around the world, but especially to the United States and Japan, both of which North Korea regards as archenemies. They recognized immediately that a missile of this type makes no sense as a weapon unless it is intended for delivery of a nuclear warhead.

A year later North Korea agreed to a moratorium on further launches, which it upheld -- until now. But there is a critical difference between now and 1998. Today North Korea openly boasts of its nuclear deterrent, has obtained six to eight bombs' worth of plutonium since 2003 and is plunging ahead to make more in its Yongbyon reactor. The six-party talks aimed at containing North Korea's weapons of mass destruction have collapsed.

Should the United States allow a country openly hostile to it and armed with nuclear weapons to perfect an intercontinental ballistic missile capable of delivering nuclear weapons to U.S. soil? We believe not. The Bush administration has unwisely ballyhooed the doctrine of "preemption," which all previous presidents have sustained as an option rather than a dogma. It has applied the doctrine to Iraq, where the intelligence pointed to a threat from weapons of mass destruction that was much smaller than the risk North Korea poses. (The actual threat from Saddam Hussein was, we now know, even smaller than believed at the time of the invasion.) But intervening before mortal threats to U.S. security can develop is surely a prudent policy.

Therefore, if North Korea persists in its launch preparations, the United States should immediately make clear its intention to strike and destroy the North Korean Taepodong missile before it can be launched. This could be accomplished, for example, by a cruise missile launched from a submarine carrying a high-explosive warhead. The blast would be similar to the one that killed terrorist leader Abu Musab al-Zarqawi in Iraq. But the effect on the Taepodong would be devastating. The multi-story, thin-skinned missile filled with high-energy fuel is itself explosive -- the U.S. airstrike would puncture the missile and probably cause it to explode. The carefully engineered test bed for North Korea's nascent nuclear missile force would be destroyed, and its attempt to retrogress to Cold War threats thwarted. There would be no damage to North Korea outside the immediate vicinity of the missile gantry.

The U.S. military has announced that it has placed some of the new missile defense interceptors deployed in Alaska and California on alert. In theory, the antiballistic missile system might succeed in smashing into the Taepodong payload as it hurtled through space after the missile booster burned out. But waiting until North Korea's ICBM is launched to interdict it is risky. First, by the time the payload was intercepted, North Korean engineers would already have obtained much of the precious flight test data they are seeking, which they could use to make a whole arsenal of missiles, hiding and protecting them from more U.S. strikes in the maze of tunnels they have dug throughout their mountainous country. Second, the U.S. defensive interceptor could reach the target only if it was flying on a test trajectory that took it into the range of the U.S. defense. Third, the U.S. system is unproven against North Korean missiles and has had an uneven record in its flight tests. A failed attempt at interception could undermine whatever deterrent value our missile defense may have.

We should not conceal our determination to strike the Taepodong if North Korea refuses to drain the fuel out and take it back to the warehouse. When they learn of it, our South Korean allies will surely not support this ultimatum -- indeed they will vigorously oppose it. The United States should accordingly make clear to the North that the South will play no role in the attack, which can be carried out entirely with U.S. forces and without use of South Korean territory. South Korea has worked hard to counter North Korea's 50-year menacing of its own country, through both military defense and negotiations, and the United States has stood with the South throughout. South Koreans should understand that U.S. territory is now also being threatened, and we must respond. Japan is likely to welcome the action but will also not lend open support or assistance. China and Russia will be shocked that North Korea's recklessness and the failure of the six-party talks have brought things to such a pass, but they will not defend North Korea.

In addition to warning our allies and partners of our determination to take out the Taepodong before it can be launched, we should warn the North Koreans. There is nothing they could do with such warning to defend the bulky, vulnerable missile on its launch pad, but they could evacuate personnel who might otherwise be harmed. The United States should emphasize that the strike, if mounted, would not be an attack on the entire country, or even its military, but only on the missile that North Korea pledged not to launch -- one designed to carry nuclear weapons. We should sharply warn North Korea against further escalation.

North Korea could respond to U.S. resolve by taking the drastic step of threatening all-out war on the Korean Peninsula. But it is unlikely to act on that threat. Why attack South Korea, which has been working to improve North-South relations (sometimes at odds with the United States) and which was openly opposing the U.S. action? An invasion of South Korea would bring about the certain end of Kim Jong Il's regime within a few bloody weeks of war, as surely he knows. Though war is unlikely, it would be prudent for the United States to enhance deterrence by introducing U.S. air and naval forces into the region at the same time it made its threat to strike the Taepodong. If North Korea opted for such a suicidal course, these extra forces would make its defeat swifter and less costly in lives -- American, South Korean and North Korean.

This is a hard measure for President Bush to take. It undoubtedly carries risk. But the risk of continuing inaction in the face of North Korea's race to threaten this country would be greater. Creative diplomacy might have avoided the need to choose between these two unattractive alternatives. Indeed, in earlier years the two of us were directly involved in negotiations with North Korea, coupled with military planning, to prevent just such an outcome. We believe diplomacy might have precluded the current situation. But diplomacy has failed, and we cannot sit by and let this deadly threat mature. A successful Taepodong launch, unopposed by the United States, its intended victim, would only embolden North Korea even further. The result would be more nuclear warheads atop more and more missiles.

Ashton B. Carter was assistant secretary of defense under President Bill Clinton and William J. Perry was secretary of defense. The writers, who conducted the North Korea policy review while in government, are now professors at Harvard and Stanford, respectively.