An overwhelming majority of those polled are against the changes to the security laws. The demonstrations against legislation have been widely supported. And, in the backwash, Abe’s popularity has also taken a nose-dive (without a matching bounce in support for the opposition).

Under Article 9, the ‘peace clause’, of its post-war constitution, Japan foreswore the use of military force as a means of settling international disputes. The Japan Self-Defense Forces (SDF) were previously restricted from using force unless directly attacked and are limited to the minimum level necessary to defend Japan. Much emphasis has been put upon defining what minimum means in drafting the new legislation that aims to transform Japan’s security posture to permit participation in collective self-defence.

In July 2014 the Abe cabinet reinterpreted the constitution to recognise limited forms of collective self-defence. The security bills that were passed through the upper house of the Diet last week will allow this reinterpretation to be implemented. This gives the SDF the right to use force to come to the aid of a ‘foreign country in a close relationship with Japan’ if ‘three new conditions’ are satisfied: the attack threatens the Japanese people’s constitutional right to ‘life, liberty and pursuit of happiness’; there are no other means to repel the attack; and the use of force is limited ‘to the minimum extent necessary’.

The security bills will also expand the scope for the SDF to provide logistical support to friendly countries and respond to ‘grey zone’ infringements of Japanese territorial waters and airspace short of an armed attack. Under pressure from the government’s junior coalition partner, the Komeito, the legislation restricts such support to non-combat zones. The laws also loosen restrictions on SDF participation in UN peacekeeping operations.

The controversial laws have seen tens of thousands of protestors take to the streets in almost daily rallies for the past few weeks, in a show of public anger on a scale rarely seen in Japan.

Opponents argue that the new laws violate Japan’s pacifist Constitution and could see the country dragged into American wars in far-flung parts of the globe. The weight of judicial opinion in Japan supports this argument.

Despite months of fierce opposition, the Abe government carried the suite of security-related bills through the upper house of the Diet (with the support of its coalition partner, Komeito, and some other minor parties). They usher in the biggest shift in Japan’s defence policy since his grandfather, Nobusuke Kishi, was in power 55 years ago.

Unable to muster support to formally amend Article 9 of the Constitution, which enshrines its pacifist sentiment, Abe opted instead to reinterpret the document for the purpose of his bills, ignoring warnings from scholars and lawyers that they are unconstitutional. The changes reinterpret the Constitution to allow Japan’s military to fight to protect its allies, which Abe argues is necessary because of threats from an increasingly belligerent China and unstable North Korea.

A small but potentially important compromise was negotiated with three minor opposition parties to include a supplementary resolution, which requires that any exercise of collective self-defence will be subject to prior Diet approval. While a supplementary resolution does not carry the binding weight of the law, future administrations would want to uphold this norm.

In our lead essay this week, Sourabh Gupta identifies the ‘two key rationalisations [that] underpin the security bills: that Japan’s external security environment is rapidly deteriorating; and that US deterrent power in Asia is diminishing, with knock-on effects for US–Japan security arrangements. Hence the imperative to reinterpret the SDF’s ‘self-defence’ and ‘use of force’ powers to enable seamless alliance cooperation and ‘pre-emptively diminish the potential for conflict by enhancing deterrence’. But both rationalisations, he adds, are contestable.

‘The withering of Japan’s security environment is a function of the insecurity generated by its own economic decline [rather than China’s rise] and its discomfiture in striking up a mutually beneficial political equation with Beijing’, he writes. Yet the pre-eminence of US hard power in Asia seems assured. So ‘escaping the post-war regime’ and its pacifist constraints, rather than deterrence, appears to provide the more likely motivation for Abe’s move. Abroad Abe trumpets the importance of the US–Japan alliance. At home he spruiks that the bills are only for defending Japan.

Any democracy including Japan, at least in theory, has to develop broad domestic agreement about how it sees its role abroad. Consensus on foreign and security policy at its base requires community agreement on what a country’s responsibilities are abroad as well as what it should not attempt to do in foreign theatres.

The problem, Gupta argues, is that the new security legislation strikes at two of three key tenets of Japanese pacifism: the dispatch and exercise of force overseas and the minimum exercise of force. The popular disquiet about the legislation centres on the unpreparedness of the young as well as the increasing legions of old in Japan for its being proper for Japan to play that role in the world, being at the side of its US ally in every skirmish in which it engages around the world. This is not a conception of Japan’s role in the world that sits comfortably with the majority of Japanese people and even many, maybe most, thoughtful internationalist conservatives.

There have been sudden, uncomfortable shifts in Japan’s national sentiment before and, now the security bullet has been bitten, Abe might carry the nation with him. But this enterprise is not without risks for Japan and its friends.

As Gupta warns, future Japanese governments would be extremely unwise if they did not limit the exercise of the right to collective self-defence to the area in the Far East specified under the US–Japan Security Treaty (Article 6) north of the Philippines. The tightening of deterrence arrangements without a strategy of comprehensive diplomatic engagement that affords a principle of mutual self-restraint with a rising potential foe is a recipe for increased insecurity, and that puts priority on reconstructing the basis of Japan’s geo-political relationship with China.

Peter Drysdale is Editor of the East Asia Forum.