Following the devastation of World War II Japan was forbidden from developing any offensive military capacity of any kind. Under Article 9 of the 1947 constitution, written under the supervision of General Douglas Macarthur, the country renounced war as an instrument for settling international disputes and declared it would never again maintain "land, sea, or air forces or another war potential".

The Japanese Self Defence Force, the subject of this week's Reciprocal Access Agreement with the ADF, gradually evolved - with the support of the US - as what was effectively a border protection force.

The allied powers, which retained a significant occupation force in Japan until 1952 just before the end of the Korean war, undertook to come to the country's defence if it was threatened.

An unintended consequence was that even after the payment of post-war reparations Japan came out ahead because its defence spending was minimal compared to its commercial competitors and trading partners. This helped fuel an economic boom that lasted for decades and led to Japan becoming the world's second largest economy after America from 1968 to 2010 when it was overtaken by China.

When, towards the end of the 20^th century, successive US administrations pressured Tokyo to invest more heavily in its own defence, military spending was increased and legislative changes were made to enable the Japanese military to offer rear echelon support to US forces operating in the region. In 2015, in the face of rising tensions in the South China Sea, new legislation was passed allowing the JSDF to participate in combat missions with its allies.

What had begun as a tiny border force now had the same freedom to operate abroad as any other military.

These changes have been accompanied by a significant growth in military capability in recent decades. Japan is understood to be "the turn of a key" away from developing a nuclear weapon and has the world's ninth largest defence budget, outspending Australia by a factor of almost two to one.

A world leader in conventional submarine capability, Japan is in the process of acquiring 146 Joint Strike Fighters which will operate in conjunction with its 155 locally produced F-15 Eagles and 62 multi-role Mitsubishi F2As.

While the JSDF, which has 252,000 active personnel and another 56,000 reserves, is only the 18^th largest military in the world, it ranks highly in terms of nations which rely on advanced technology rather than just strength of numbers.

Japan is a significant military power which has made a clear commitment to work with the US, the UK, Australia and other democracies with interests in the region in pushing back against Chinese aggression.

And, while Beijing will be far from happy with this development which could ultimately see Japan invited to join the "five eyes" intelligence sharing network, Xi Jinping has only himself to thank. The talks that culminated in the agreement were initiated by then PM Tony Abbot and then Japanese PM Shinzo Abe in 2014 just months after China declared its controversial Air Defence Identification Zone over the East China Sea.

Coming on top of AUKUS, the rise of "the quad" and pushback against Chinese attempts to exert influence in the Solomon Islands and other parts of Oceania, the Reciprocal Access Agreement is not something Xi Jinping can afford to dismiss lightly.

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