Arguably, the U.S.-Japan alliance has never been better. Building on efforts begun in the latter years of the Clinton administration-and accelerated on President George W. Bush's watch by a combination of unforeseen events and determined efforts on both sides of the Pacific-bilateral security ties between Tokyo and Washington have expanded beyond all expectations. As both Japanese Prime Minister Junichiro Koizumi and President Bush look back over the last five years, they can take satisfaction in knowing that they have taken bold steps toward developing the U.S.-Japan alliance into a truly global partnership, capable of addressing more international security challenges than ever before.

Of course, there are still challenges to be met, and areas in which the bilateral security relationship has room to grow. But the progress of the last few years will provide a solid foundation upon which to confront the inevitable troubles, political or otherwise, that rock any relationship. Moreover, it sets the stage for a future solidification of the strategic partnership, should both countries decide that it is in their best interest to do so.

It would not be an exaggeration to say that the terrorist attacks of September 11, 2001, were a seismic event in Tokyo-Washington ties. In the days after 9/11, Japan took the unprecedented step of offering to deploy a flotilla of Japanese Maritime Self-Defense Force (JMSDF) support ships to the northern Arabian Sea to provide fuel oil to U.S. Navy ships involved in military operations in Afghanistan against the Taliban and al-Qaeda-Japan's first out of area, non-peacekeeping operation in post-World War II history. The initial six-month operation approved by the Japanese Diet under a special anti-terrorism law was passed in record time, and included an additional appropriation of $100 million for fuel oil. The special legislation was subsequently renewed several times for additional six-month periods, and eventually included the deployment of an Aegis-equipped Kongo-class destroyer as well. This show of political will in support of Washington gave teeth to Tokyo's famous "checkbook diplomacy," overcoming the historic criticism of Japan for its lack of concrete involvement in the 1991 Gulf War.

In the years since, Japan has made other contributions to the War on Terror. Following the conclusion of major combat operations in Iraq, Tokyo contributed $5 billion to the reconstruction effort, and led an independent effort to pressure Persian Gulf states to match its donation. In 2003, Tokyo also dispatched Japanese Ground Self-Defense Forces (JGSDF) to Samawah in southern Iraq for reconstruction duties. In all, some 5,500 Japanese soldiers in 600-man detachments participated in the two-and-a-half-year deployment, making it the largest overseas deployment of the JGSDF in its history. Fortunately for sensitive Japanese public opinion, the unit saw no military action in Iraq. And today, even as the JGSDF draws down its contingent, the Japanese Air Self-Defense Force's C-130 aircraft based in Kuwait will increase its operational tempo in support of multinational forces in Iraq.

There has also been significant progress between Washington and Tokyo on another area of critical importance: missile defense. Since North Korea's unexpected launch of a Taepo-Dong intercontinental ballistic missile over Japan in 1998, the Japanese government has been engaged in missile defense cooperation with the United States. But, when President Bush took office, that program was in serious trouble. The Japanese Defense Agency had become increasingly skeptical of Washington's long-term commitment to missile defense. The Pentagon's Missile Defense Agency was equally frustrated with Japanese foot-dragging on commitments beyond simply joint research. The joint research program was almost defunded by the Pentagon in 2001. Fortunately, strong political leadership on missile defense by President Bush, as well as robust military diplomacy on the part of the Pentagon, rescued the joint effort from the dustbin of history.

Missile defense cooperation, spurred by China's unprecedented military build-up and North Korea's expanding nuclear and ballistic missile capabilities, has intensified dramatically in recent years. Japan has agreed to move from development to deployment of anti-missile capabilities, agreeing to outfit its Aegis-equipped destroyers with SM-3 interceptors, placing an X-band missile defense radar array in Japan, and upgrading its theater missile defense units to the next generation of the U.S. Patriot system. In another first, in June 2006, a Japanese Aegis-equipped destroyer participated in a successful joint missile defense exercise off Hawaii, providing accurate surveillance and tracking for the American Aegis-equipped "shooter."

These monumental advances, moreover, are likely to be only the beginning. There can be no doubt that a strong desire exists on the part of both the Bush and Koizumi governments not only to preserve the gains made thus far, but to improve upon them. The June 2006 Bush-Koizumi summit held in the United States yielded a joint declaration identifying common interests and objectives for the partnership-and laying an ambitious theoretical basis for the alliance's future.

These days, perhaps nothing is driving Tokyo and Washington into each other's arms more forcefully than North Korea's rogue behavior, most recently manifested by the DPRK's July 4th launch of seven ballistic missiles of various ranges into the Sea of Japan (some of which reportedly landed within Japan's 200-mile Exclusive Economic Zone). In fact, North Korea has been the principal motivation for a reinvigorated security relationship between Japan and the United States for over a decade. Over the years, events like the 1994 North Korean nuclear crisis and North Korea's 1998 Taepo-Dong launch have helped politicos and foreign policy elites in both capitals to rediscover the enduring importance of the post-Cold War American-Japanese alliance. Tokyo has come to fundamentally understand that Japan is as much in the cross-hairs of North Korea's nuclear and missile programs as are the United States and South Korea. In truth, considering Pyongyang's current inability to strike the United States and its probable reluctance to attack its brethren in South Korea, Japan may be the nation that is today most threatened.

North Korea is not the only reason for U.S.-Japanese convergence, however. The rise of China is also creating a new focus in Washington and Tokyo. While neither country is looking to make China its next enemy, both understand that the ascendance of a new power can be a disruptive occurrence. While Chinese strategic intentions, by some estimates, are ambiguous, the significance of Beijing's growing military capabilities is not. China now has the world's third largest defense budget, and while figures are inexact due to a lack of transparency in the Chinese military budget, the Pentagon estimates Beijing's defense spending to be in the $70-90 billion per year range, according to its 2005 Annual Report to Congress on the Military Power of the People's Republic of China. Perhaps even more troubling is the rate at which Chinese defense spending is growing-10 percent or more a year for over a decade. Washington and Tokyo must be asking themselves what Beijing plans to do with the fruits of the world's fastest growing peacetime defense budget.

The issue of Taiwan has also come into focus on the Japanese security horizon. While Tokyo has long opted to remain low-key on the Taiwan issue for fear of upsetting Beijing, Japan has taken a public interest in stability across the Taiwan Strait. The deterioration in Sino-Japanese relations in recent years, coupled with the rise of Chinese political, economic and military power, has led to deep concerns in Japan about Chinese intentions.

But deepening the Washington-Tokyo relationship won't necessarily be easy. There are plenty of obstacles that both sides, but especially Tokyo, will need to navigate. At the top of the list is the upcoming change in leadership slated to take place in both countries. Japan's current Prime Minister, Junichiro Koizumi, will step down in September, and candidates are already lining up for the 2008 presidential race. These political changes could substantially alter the Japanese-American alliance. While Bush and Koizumi "clicked" from the very beginning, as evidenced by frequent meetings, playing catch at Camp David, and Koizumi's now-famous trip to Elvis Presley's home at Graceland, there is no guarantee that future Japanese and American leaders will have this sort of close personal-and working-relationship.

There could also be a shift in policy emphasis. Five years on, it is easy to forget how the Clinton administration viewed Japan during its tenure. While some, particularly in the Pentagon, saw Japan as critical to regional security, the Clinton White House opted to put China squarely at the center of its Asia policy. Naturally, relations with Japan soured. While the Bush administration's Asia policy has been firmly focused on Japan from day one, a change in the White House in 2009 could easily bring with it a similar shift in focus.

The basing of some 50,000 U.S. forces in Japan, especially on Okinawa, also continues to be a potential flashpoint. While Tokyo and Washington have tried to be responsive to Japanese locals over the years about the noise generated by aircraft and helicopters and the occasional crimes committed by American service members, the domestic outcry continues. Both the U.S. and Japan fundamentally understand the importance of the presence of American forces in Japan to the defense of Japan, a North Korean contingency and as a hedge against China's military build-up. But despite creative solutions proposed by both sides (such as the redeployment of 8,000 Marines and 9,000 dependents from Okinawa to Guam), problems remain. In some cases, it is the local Japanese who are the problem. In others, it is U.S. congressional objections over financial "burden-sharing" and host nation support. And sometimes, it is Japanese domestic politics or tight purse strings in Tokyo that get in the way. Whatever the reasons, finding the right fit for a continued U.S. military presence in Japan will be a thorny subject for the foreseeable future.

A deepening of ties also is potentially hampered by Japan's pacifist constitution. Drafted in the aftermath of World War II by American occupiers, Article 9 of the Japanese constitution forbids Japan from using military force as an instrument of foreign policy to settle disputes, but allows the country to defend itself. By long-standing interpretation, Article 9 also prevents Japan from involving itself in collective self-defense. According to current views, Japanese forces may only be used in the defense of Japan, hence their non-threatening name. There is no Japanese army, navy or air force per se, but rather contingents of Self-Defense Forces. Currently, Japanese forces do not even have the constitutional authority to defend U.S. forces, unless doing so was seen as contributing to the defense of Japan. The U.S.-Japan Mutual Security Treaty is not, in fact, a "mutual" defense pact, like NATO's formative document, the North Atlantic Treaty, where an armed attack on one is interpreted as an armed attack on all. Should the United States come under attack, Japan is under no obligation to come to America's defense. It might do so, but under current circumstances the Japanese parliament, or Diet, would have to pass legislation to allow Japanese forces to exceed their current constitutional mandate. And in the past, with the possible exception of special anti-terrorist legislation passed in the aftermath of 9/11, this legislative process has been highly politicized and painfully slow.

Nevertheless, change may be on the horizon. While Japan largely considers itself a pacifist nation, the summer 2006 North Korean missile launches may have precipitated a significant shift in Japanese security thinking. In the days after North Korea launched its missiles into the Sea of Japan, several senior Japanese officials, including the government's leading spokesman, Chief Cabinet Secretary Shinzo Abe, announced that Japan should look at its constitution to see whether it would allow for developing the military capabilities to launch a pre-emptive attack against North Korean missile facilities as an act of self-defense. Abe, the front-runner to replace Koizumi as premier, has been a leading voice in Japanese conservative political circles to revise the constitution to allow Japan to build armed forces commensurate with Japan's political and economic role in the world. And Abe is not alone; the head of the Japanese Defense Agency, Fukushiro Nukaga, has also publicly supported such a re-conception of the use of force "if an enemy country definitely has a way of attacking Japan and has its finger on the trigger."[1]

Some analysts believe that conservative politicians like Abe may be seizing on the North Korean missile tests in hopes that public anger will increase support for revising the constitution. But while these comments are striking, they are not entirely unexpected. In recent years, Japanese government officials have begun openly discussing whether Japan should add offensive weapons, such as air- and sea-launched cruise missiles, to its military arsenal. In February 2003, Defense Minister Shigeru Ishiba warned that Japan would attack North Korea if it had evidence Pyongyang was preparing to launch ballistic missiles, going so far as to indicate that Japan could regard the process of fueling a missile as the start of military attack, according to an interview with Reuters. Ishiba's statement, at that time absent a provocation similar to the July 2006 missile tests, may have sent tremors throughout East Asia, but, equally importantly, it was a telling indicator of Japan's growing frustration with-and worry over-Pyongyang's behavior.

Clearly, Japan is rethinking its security. Not everyone in the region will view Japan's efforts in the same way. While the U.S. may see Japan's desire to expand its contributions to international security in the context of the bilateral alliance as a net benefit, other Asian neighbors may view it as provocative, especially considering Japan's militarism during the 20th century. Despite the relatively small size of Japan's armed forces (which number some 240,000) compared with other regional militaries, outcry from China as well as South Korea could potentially slow Japan's efforts to become a more "normal" nation. While Beijing and Seoul cannot directly affect the pace of change in Japan's security policy, a desire to avoid public controversy over its past history may play a role in slowing the pace of change in Tokyo's security thinking.

And there is no doubt that there will be a significant debate within Japan about hitching itself more fully to America's wagon. U.S. foreign policy in Japan is not without controversy. While the invasion of Afghanistan after 9/11 was popular and deemed to be fully justified, the American invasion of Iraq in 2003 received only mixed support. And the fact that the Iraq war has dragged on for over three years now has convinced the average Japanese that the United States is not omniscient-or omnipotent. While the United States and Japan share many similar values, because of the ongoing challenges in Iraq there is a healthy dose of skepticism among the Japanese public about being swept up in American "adventurism" overseas that may not directly benefit perceived Japanese interests. For instance, some Japanese scholars, while generally concerned about the rise of China, have no interest in getting involved in a Sino-American donnybrook over Taiwan's future, especially if Taipei mismanages cross-Strait relations. Of course, other Japanese security specialists realize that the disposition of Taiwan's future could have a serious effect on Japan too, noting that the island nation is a strategic piece of real estate connecting Northeast Asian and Southeast Asian sea lanes, on which Japan is heavily dependent, especially for its energy needs.

But there are a number of international security threats upon which the United States and Japan can certainly agree. Islamic terrorism, sea piracy and the proliferation of weapons of mass destruction are critical issues for both countries, and there has been notable progress in some of these areas, including Tokyo's accession to the Bush administration's premier counterproliferation partnership, the Proliferation Security Initiative (PSI). Yet, so far, these advances have been ad hoc in nature. In the future, both sides need to seek ways to build upon them by forging a durable, global partnership capable of advancing mutual interests.

It makes sense that two of the world's most powerful democracies, which share common interests and values such as economic and political freedom, should work together to advance stability, security and prosperity in Asia-and beyond. This won't necessarily be easy, but it should certainly be endeavored.

The U.S.-Japan alliance, while not perfect, is much more ready to face 21st century threats than it was just five years ago. There is still room for improvement in terms of bilateral coordination, planning and interoperability. Political constraints are also present; absent a crisis such as another North Korean provocation, it is unlikely that there will be much more progress in the bilateral security relationship while Japan transitions to new leadership. But the political transition to the post-Koizumi era won't last forever, and Japan will need to make some difficult decisions in the years ahead if it wants the bilateral security relationship to grow beyond the Bush-Koizumi legacy. For right now, Washington is a willing partner in this endeavor, and holds high hopes for further progress.

As such, the future of the bilateral security relationship by and large rests in Japan's hands. With appropriate attention, proper tending and enlightened leadership, the alliance has the potential to become the bedrock of peace and stability in the Asia-Pacific region, as well as a powerful force for dealing with both regional and global challenges. It is up to officials in Tokyo to make this vision a reality.

Peter Brookes is a columnist forThe New York Post, a Heritage Foundation senior fellow and author of "A Devil's Triangle: Terrorism, WMD and Rogue States."

[1] Martin Fackler, "Tokyo Talks of Military Strike on North Korea," International Herald Tribune, July 10, 2006, http://www.iht.com/articles/2006/07/10/news/japan.php.