The new Anglo-Japanese defense agreement is a message to Moscow and Beijing

In 1902, Britain broke out of what had been its longstanding policy of non-alignment, what it termed “splendid isolation,” and created its first alliance with a foreign power, the Japanese Empire. It subsequently renewed and expanded the treaty twice more, in 1905 and 1911. The alliance was meant to serve as a deterrent to Russian expansion in China and Korea. Soon enough, Japan would find itself at war with Russia, which it defeated in 1905.

Fast forward a century later and, after having been adversaries in World War II, the two countries have announced another defense agreement, motivated as in the past by Russian aggression — but this time with Chinese, as well as Russian, adventurism as a primary target. The defense pact, formally termed a Reciprocal Access Agreement, does not mention Beijing or Moscow explicitly, but it provides for joint training, disaster relief cooperation and, most importantly, reciprocal accelerated troop deployments.

Neither Prime Minister Boris Johnson nor his Japanese counterpart, Fumio Kishida, has equivocated as to what the agreement is about. Speaking at 10 Downing St., where the two leaders met on May 5, Johnson stressed the need to have allies in Europe and East Asia stand together in the face of what he called “autocratic, coercive powers.” Kishida underscored the importance of standing together to challenge Russia’s invasion of Ukraine in order to deter a potential Chinese attack on Taiwan.

The agreement marks a noteworthy change for both countries, as its forerunner did a century ago. Since the end of World War II, and governed by its pacifist constitution, Japan has been reluctant to enmesh itself in foreign disputes. Its focus instead has been on providing humanitarian and development assistance to countries ravaged by war. It did so in the Balkans during the late 1990s and in Iraq in the first decade of this century.

Yet, in recent years, Japan has become increasingly outspoken about China’s intentions regarding Taiwan, once a Japanese colony that bore the name Formosa. It was not all that long ago that Japan was reluctant to commit publicly to anything that even remotely smacked of its willingness to come to the island democracy’s defense in the event of a Chinese cross-straits attack. That is changing, as the prime minister’s comments at Downing Street made clear.

At the same time, Tokyo’s willingness to impose far tougher sanctions on Moscow, and to freeze Russian assets, in the aftermath of Russia’s invasion of Ukraine marks a far stronger response to Moscow’s aggression than was the case in the past. Nor was Japan fazed by Moscow’s decision to break off talks with Tokyo over the future of the four Kuril islands, over which the two countries remain at loggerheads, and which is a major reason why they have yet to sign a peace treaty formally to end World War II (the state of war between them ended in 1956).

Japan has stepped up its military involvement with nations other than the United States, most notably its involvement in the Quad, which includes not only America, but also Australia and India. The agreement with Britain marks another step in Japan’s emergence on the international scene as not only an economic powerhouse but as a significant politico-military player as well, in East Asia and in Europe.

The agreement also marks a major initiative for Britain, whose only defense relationship of note in East Asia was the more than half-century old, low-profile Five Powers Defense

Arrangements with Singapore, Malaysia, New Zealand and Australia. Britain’s focus had shifted primarily to Europe when, five years before it joined what was then called the European Economic Community in1973, the Labour Government decided to withdraw Britain’s military presence “East of Suez.”

In recent years, Britain began conducting naval deployments through the South China Sea to register its support for maintaining it as a free and open international waterway. But its agreement with Japan returns it full force to the East Asian theater. Indeed, the new Anglo-Japanese agreement builds on Britain’s defense agreements with the United States and Australia in the AUKUS submarine and high technology arrangement and, as noted, with Canberra via the Five Powers Defense Arrangements. As a result, Britain now has formal defense agreements with three of the four Quad members, and it is those states — Japan, Australia and the United States — that are most openly critical of China’s adventurism.

The British military may no longer be as overwhelming as it was when the Anglo-Japanese alliance came into being, but the United Kingdom remains one of the world’s military powers and its re-entry into East Asia should not be minimized. Just as Moscow has had no choice but to take notice of Japan’s actions in support of Ukraine, so, too, Beijing would be wise to do the same regarding London’s new agreement with Tokyo.

Dov S. Zakheim is a senior adviser at the Center for Strategic and International Studies and vice chairman of the board for the Foreign Policy Research Institute. He was under secretary of Defense (comptroller) and chief financial officer for the Department of Defense from 2001 to 2004 and a deputy under secretary of Defense from 1985 to 1987.