The Japan-India security agreement signed recently marks a significant milestone in building Asian power equilibrium. A constellation of Asian states linked by strategic cooperation and with shared common interests is becoming critical to instituting stability at a time when major shifts in economic and political power are accentuating Asia’s security challenges.

What Tokyo and New Delhi have signed is a framework agreement that is to be followed by "an action plan with specific measures to advance security cooperation" in particular areas, ranging from sea-lane safety and defense collaboration to disaster management and counterterrorism. How momentous this Oct. 22 accord is can be seen from the fact that Japan has such a security agreement with only one other country — Australia.

Tokyo, of course, has been tied to the United States militarily since 1951 through a treaty designed to meet American demands that U.S. troops remain stationed in Japan even after the American occupation ended. Today that treaty — revised in 1960 — is a linchpin of the American forward-military deployment strategy in the Asian theater.

The Indo-Japanese defense accord adds another pillar to the idea of building quadrilateral strategic cooperation among the four major democracies in the Asia-Pacific region — Australia, India, Japan and the U.S. The only missing link in this quad is an Australia-India defense pact. The three states other than India are not only tied together through bilateral security arrangements, but also have a trilateral strategic-dialogue mechanism.

India, Japan and the U.S., for their part, held their first trilateral naval maneuvers near Tokyo in April 2007, and the three then teamed with Australia and Singapore for major war games in the Bay of Bengal five months later. Furthermore, the close coordination established among the Indian, Japanese, Australian and U.S. military contingents in rescue operations following the December 2004 Indian Ocean tsunami helped spawn a disaster-relief mission.

It is only a matter of time before Australia and India forge closer defense ties. Canberra actually took an important first step in that direction by initialing a memorandum of understanding on defense cooperation with New Delhi in 2006. This was followed by a bilateral arrangement to share classified information on maritime security, fragile states, counterterrorism and peacekeeping.

During a recent visit to India, Foreign Minister Stephen Smith said: "Australia wants to further strengthen our defense links with India, and we are particularly pleased to have reached an agreement this year that our chiefs of defense forces will meet annually."

The Indo-Japanese security agreement, signed during Indian Prime Minister Manmohan Singh’s visit to Tokyo, is modeled on the March 2007 Japan-Australia defense accord. Both are in the form of a joint declaration on security cooperation. And both, while recognizing a common commitment to democracy, freedom, human rights and the rule of law, obligate the two sides to work together to build not just bilateral defense cooperation, but also security in the Asia-Pacific.

But unlike distant Australia with its relatively benign security environment, India and Japan are China’s next-door neighbors and worry that Beijing’s accumulating power and growing assertiveness could create a Sino-centric Asia. Canberra, in contrast, wishes to balance its relations with Tokyo and Beijing, and loves to cite the new reality that, for the first time, Australia’s largest trading partner (China) is no longer the same as its main security anchor (U.S.).

But there is nothing unique about this situation. It is a testament to Beijing’s rising global economic clout that China is also Japan’s largest trade partner and is poised to similarly become India’s in a couple of years. On the other hand, two of India’s most-important bilateral relationships — with Russia and Japan — suffer from hideously low trade volumes.

Trade in today’s market-driven world is not constrained by political differences — unless political barriers have been erected, as the U.S. has done against Cuba and Burma, for example. In fact, as world history testifies, booming trade is not a guarantee of moderation and restraint between states. The new global fault lines show that that it was a mistake to believe that greater economic interdependence by itself would improve international geopolitics. Better politics is as important as better economics.

Close security ties, however, serve as the bedrock of an economic partnership, as between America and Japan, and between the U.S. and Europe.

Canberra has consciously sought to downplay its defense accord with Tokyo to the extent that, nearly a year after Prime Minister Kevin Rudd took office, a visitor seeking to access the text of that agreement on the Department of Foreign Affairs and Trade (DFAT) Web site is greeted by this message: "Sorry, the page you asked for has been temporarily removed from the site. . . . Following the recent Australian federal election, the content of this page is under review until further notice." Indeed, Rudd’s Labor Party, while in the opposition ranks, had openly cast doubt on the utility and wisdom of that agreement.

In that light, it is no surprise that beyond their similarly structured format, including the mirrored requirement for a followup action plan, the Japanese-Australian and Indo-Japanese agreements carry different strategic import. The one between Tokyo and New Delhi is plainly designed to contribute to Asian power equilibrium. The partnership, as the two prime ministers said in their separate Oct. 22 joint statement, forms an "essential pillar for the future architecture" of security in the Asia-Pacific.

By contrast, the Australian-Japanese agreement carries little potential to become an abiding element of a future Asia-Pacific security architecture, given the two parties’ contrasting strategic motivations and Canberra’s attempts from the outset to package it as a functional arrangement devoid of geopolitical aims.

Tellingly, the push for that accord had come from then Japanese Prime Minister Shinzo Abe, the architect of the Quadrilateral Initiative — founded on the concept of democratic peace. And it was the Mandarin-speaking Rudd who this year pulled the plug on that nascent initiative, which had held only one meeting.

In fact, the significance of the Indo-Japanese agreement truly parallels the 2005 Indo-U.S. defense framework accord, which signaled a major transformation of the once-estranged relationship between the world’s most-populous and most-powerful democracies. Both those agreements focus on counterterrorism, disaster response, safety of sea lanes, nonproliferation, bilateral and multilateral military exercises, peace operations, and defense dialogue and cooperation. But the former has not only been signed at a higher level — prime ministerial — but also comes with a key element: "policy coordination on regional affairs in the Asia-Pacific region and on long-term strategic and global issues."

This is an agreement between equals on enhancing mutual security. By contrast, the U.S.-India defense agreement, with its emphasis on U.S. arms sales, force interoperability and intelligence sharing, aims to build India as a new junior partner (or spoke) as part of a web of interlocking bilateral arrangements that mesh with America’s hub-and-spoke global alliance system undergirding U.S. interests.

It is doubtful, however, that the U.S., despite the defense accord and the subsequent nuclear deal, would succeed in roping in India as a new ally in a patron-client framework. In a fast-changing world characterized by a qualitative reordering of power — with even Tokyo and Berlin seeking to discreetly reclaim their foreign-policy autonomy — U.S. policymakers are unlikely to be able to mold India into a Japan or Germany to America.

In keeping with its long-standing preference for strategic independence, India is likely to retain the option to forge different partnerships with varied players to pursue a variety of interests in diverse settings. That means it is likely to become multialigned.

The security agreement with Japan — still the world’s second-largest economic powerhouse after the U.S. — jibes well with India’s desire to pursue omnidirectional cooperation for mutual benefit with key players.

Japan and India indeed are natural allies, with no negative historical legacy and no conflict of strategic interest. Rather, they share common goals to build stability and institutionalized cooperation in Asia and make the 20th-century international institutions and rules more suitable for the 21st-century world. They are establishing a "strategic and global partnership" that is driven, as their new agreement states, "by converging long-term political, economic and strategic interests, aspirations and concerns."

Both countries are energy-poor and heavily dependent on oil imports by sea from the Persian Gulf region. They are seriously concerned by mercantilist efforts to assert control over energy supplies and transport routes.

Such is the fast-developing nature of their relationship that the two, besides holding a yearly summit meeting, have now instituted multiple strategic dialogues involving their foreign and defense ministers and national security advisers, as well as "service-to-service exchanges including bilateral and multilateral exercises." The Indian and Japanese space agencies are also to cooperate as part of capacity-building efforts in disaster management.

The proposed broad-based strategic collaboration makes sense because the balance of power in Asia will be determined as much by events along the Indian Ocean rim as in East Asia.

However, it will be simplistic to see such cooperation one-dimensionally as aimed at countervailing China’s growing might. Beijing itself is pursuing a range of bilateral and multilateral initiatives in Asia to underpin its strategic objectives and help shape Asian security trends — from weapon sales to countries from Iran to Indonesia and port-building along the Indian Ocean rim, to the Shanghai Cooperation Organization and strategic corridors through Pakistan and Burma.

Given China’s territorial size, population (one-fifth of the human race) and economic dynamism, few can question or begrudge its right to be a world power. In fact, such is its sense of where it wishes to go that China cannot be dissuaded from the notion that it is destined to emerge, to quote then President Jiang Zemin, as "a world power second to none."

Yet at the core of the challenge that an opaque China poses to Asian stability is the need for like-minded states to engineer subtle limits that could help forestall Chinese power from sliding into arrogance or strategic confrontation. With U.S. clout in Asia beginning to erode and American interests getting increasingly intertwined with the Chinese economy, Japan and India are interested not in gaining pre-eminence in Asia but in thwarting ambitions of pre-eminence.

Against that background, why begrudge the efforts of Asia’s two largest and most-established democracies to work together to avert Asian power disequilibrium? Never before in history have China, India and Japan all been strong at the same time.

Today, they need to find ways to reconcile their interests in Asia so that they can peacefully coexist and prosper. But there can be no denying that these three leading Asian powers and the U.S. have different playbooks: America wants a unipolar world but a multipolar Asia; China seeks a multipolar world but a unipolar Asia; and India and Japan desire a multipolar Asia and multipolar world.

Brahma Chellaney, professor of strategic studies at the privately funded Center for Policy Research in New Delhi, is the author, most recently, of "Asian Juggernaut: The Rise of China, India and Japan."