The United States and Japan announced their new Guidelines for Defense Cooperation on the eve of Prime Minister Shinzo Abe’s visit to Washington. The agreement institutes sweeping changes to the existing 1997 guidelines, enabling greater synergistic and integrated alliance security operations worldwide. The announcement marks a major accomplishment for the alliance and provides a strong foundation for Abe’s summit meeting with President Obama.

The United States has long urged Japan to play a larger role in addressing international security challenges—one commensurate with its economic size and international political gravitas. But since 1945, Japanese Self-Defense Forces (SDF) have been constrained by constitutional, legislative and budgetary restrictions. Tokyo also eschewed exercising collective self-defense—the ability to defend the forces of another country—a right guaranteed to all nations under the UN Charter. As a result, Japan was precluded, for example, from protecting U.S. forces deployed to defend Japan or even transporting American bullets on Japanese ships.

Under existing legislation, Japan can provide rear area logistical support only to U.S. forces in areas surrounding Japan, most notably for an emergency on the Korean Peninsula. Moreover, deploying SDF for international peacekeeping operations has been cumbersome due to protracted legislative debate. Even benign operations such as transporting oil in the Indian Ocean have required extensive discussion. And, Japan typically would withdraw its forces if a peacekeeping assignment became dangerous.

In sum, the 1997 alliance guidelines were hopelessly outdated for dealing with today’s evolving and deteriorating security environment. Concepts such as “rear area” were no longer valid in light of North Korea's growing nuclear and missile capabilities as well as new threats such as cyber warfare and the militarization of space. Japanese security roles, missions and capabilities have also evolved since 1997, with the SDF gradually expanding into new areas.

Prime Minister Abe, while pursuing security policies largely consistent with his predecessors, brought a new vitality to implementing long-promised reforms. His advocacy for Japan exercising collective self-defense provided the catalyst for updating the alliance guidelines. The two are inexorably linked, however, with the expanded alliance guidelines dependent on Abe achieving new domestic legislation to enable collective self-defense.

The new defense guidelines expand both the geographic scope and nature of Japan’s security contributions. Gone are the limits on Japan providing logistical support only near Japan. Gone also is the restriction that limited Japan to assisting U.S. forces only. Instead, Tokyo may conduct operations “involving the use of force... where an armed attack against a foreign country that is in a close relationship with Japan occurs.”

Japan can now, for example, intercept North Korean ballistic missiles bound for U.S. targets and defend allied ships from North Korean submarines as they provide missile defense to Japan. The concept of Japanese self-defense will now take on a more global scope, possibly including defending sea lines of communication in the Strait of Hormuz.

The new alliance guidelines, in conjunction with Japan exercising collective self-defense, will provide a welcome and long overdue augmentation of allied security capabilities against growing security threats in Asia and worldwide. Japan's archaic and overly restrictive interpretation of its constitution has prevented Tokyo from being a viable contributor to UN peacekeeping operations.

The changes, though monumental in a Japanese context, are still only incremental steps toward principles that all other nations already operate by. As such, it is not a slippery slope toward Japan becoming involved in combat operations or a resurgent militarism as some have charged.

When announcing his administration’s new policy on collective self-defense last July, Abe declared, “It still remains the case that the SDF will never participate in such warfare as the Gulf War or the Iraq War…. Japan will never become a country that would wage war again.” This is consistent with all other Japanese documents which underscore that Japan shall not engage in offensive operations.

The Japanese SDF will still remain extremely constrained in its operations. For example, Japan will not have the ability to strike foreign bases, conduct expeditionary operations, or possess the strategic airlift capabilities required to project power overseas. At a time when China has increased its defense expenditures by 170 percent in the past 10 years, Japan's defense expenditures have declined by 0.2 percent.

The new guidelines emphasize that when the United States and Japan use force, it will be done in accordance with international law and with “full respect for sovereignty” – a code phrase for requiring South Korean permission prior to approaching the Korean Peninsula.

Quite simply, the United States and South Korea cannot deter and defend the Korean Peninsula from the North Korean threat without the critical support of Japan. The seven UN Command-designated bases in Japan are an irreplaceable component of any allied contingency, as are other Japanese bases.

In a Korean crisis, Japan would be the transportation and logistical rear base for American reinforcements en route to the Korean Peninsula. Japan would also be expected to contribute to defending the air- and sea-lines of communication for the United States and to South Korea. Japan not exercising collective self-defense could unnecessarily put U.S. forces in harm’s way or prevent Tokyo from providing important logistics support to the allies during a Korean conflict.

The new Guidelines for Defense Cooperation will expand Japan's global security role and provide greater flexibility, responsiveness and interoperability for alliance training, exercises, and planning on a broader spectrum of security issues. But questions remain as to whether Japan can fulfill these new or existing missions with current forces. Washington has long urged Japan to increase its defense expenditures.

While Washington strongly supports Tokyo assuming a larger international security role, Japan’s neighbors remain wary. The United States and Japan have a responsibility to augment public diplomacy efforts to assuage regional concerns, particularly those of South Korea. One way to reassure Seoul of Japanese intentions would be to more closely coordinate or integrate bilateral and trilateral security operations. But recently Seoul has been reluctant to do so, even reducing previously agreed upon cooperative security activities.

There are indeed growing security threats in Asia, but Japan exercising collective self-defense and assuming a larger security role is not one of them. Japan acting collectively in concert with partners for defensive purposes rather than unilaterally for offensive objectives are in Asia’s and the world’s best interests.

 - Bruce Klingner is the Senior Research Fellow for Northeast Asia at The Heritage Foundation's Asian Studies Center.