It was a sign of how divided Japanese politics had become. In September, physical altercations broke out between members of the usually sedate House of Councillors as the country’s upper parliamentary chamber voted 148-90 in favour of a controversial bill that would allow the military to engage in combat overseas. With 13,000 people gathered outside to protest Prime Minister Shinzo Abe’s constitutional changes, politicians pushed and shoved each other as the chairman desperately tried to maintain order among the rowdy lawmakers.

The scenes were the culmination of a drawn out political struggle in Japan over the potential removal of a controversial clause in the country’s constitution, which, in theory, makes it an officially pacifistic nation.

Article 9 came into effect on 3 May 1947 in a nation devastated by war. In a bold move not taken by any other defeated power, it formally renounces Japan’s right to wage war overseas and emphasises its commitment to a world order governed by peace and stability, not countries fighting for dominance. In practice, this has meant that while the country does maintain modest self-defence forces, they are not allowed to engage in combat abroad.

Abe’s policy does not abolish Article 9 but reinterprets it, allowing Japanese troops to fight in peacekeeping missions or in the defence of an ally – a change critics fear might lead to soldiers dying in foreign entanglements. Under the new rules, troops can be mobilised provided that the conflict meets three conditions: Japan or a close ally is attacked and the result "threatens Japan’s survival and poses a clear danger to people", there is no other way to repel the attack without the use of force and the use of force is the only option.

It’s certainly the case that the Japanese are constantly nervous that they might wake up one day to discover America has embraced China as the indispensable partner and that Japanese interests would be neglected.

Despite these caveats, carefully crafted by legislators during the months that the bill has taken to go through parliament, the majority of Japanese citizens oppose the proposed changes.

Many question why, as Japan continues to face a stagnant economy and myriad social and political problems, Abe’s government has chosen to invest so much political capital in such a controversial cause.

There are a number of reasons. Former UK Ambassador to Japan Sir David Warren broadly approves of the move, and argues that the rush to pass this legislation lies in the country’s growing insecurity about where it stands in East Asia. Many in Japan fear that the US, once a stalwart ally, is no longer as serious about their protection as it once was, and that in the face of an increasingly assertive China, Japan may have to fend for itself.

"Abe wants to do everything he can to ensure Japan is in a position to burden share the way the Americans would want them to," he says. "It’s certainly the case that the Japanese are constantly nervous that they might wake up one day to discover America has embraced China as the indispensable partner and that Japanese interests would be neglected."

The execution of the journalist Kenji Goto at the hands of ISIS and the death of NGO worker Hoshi Kunio in Bangladesh have hammered home the idea that Japanese citizens are now targets abroad for the simple reason of their citizenship. Warren argues that this reality has contributed to a sense that, despite its pacifist traditions, the country may need to become more assertive abroad and when protecting its citizens.

There are also political motivations behind the policy change. Abe’s Liberal Democratic Party (LDP) is under intense pressure from right-wing forces in Japan, and in the past he has associated with the more reactionary – and historically revisionist – factions within his party. Unlike some of his LDP predecessors, Abe and his allies have always been hawkish on foreign policy, but Warren warns against ascribing all motivations for the change in the law to pure chauvinism.

"I do think that Abe governs in a pragmatic way," he says. "I wouldn’t attribute his insistence on this security reform to unthinking following of a nationalist agenda.

"There’s a nationalist objective there, but I think it’s always tempered by a sense that he needs to be pragmatic as well, and on the whole, the head comes out over the heart in the way that he pushes that policy forward."

Military might
Abe has good reason to be concerned about his neighbours. Under Xi Jinping, China has sought to complement its new status as a massive economic power with military might, ramping up nationalist rhetoric and the assertiveness of its armed forces in territorial disputes. It’s no surprise that China has been highly critical of the changes to Japan’s military policy.

These developments stir mixed feelings in Japan. The two countries are critical to each other’s development, as China is Japan’s largest trading partner, and China benefits from the consumer demand which comes from one of its most prosperous neighbours. But there’s also a sense that China is a source of instability; and history remains fresh in the minds of both sides. In the eyes of many, the changes to the law are a sign of a resurgent imperial Japan.

"There’s a perception in Japan that China is a power that is consciously challenging the status quo in the Asia-Pacific region," argues Warren. "In its territorial claims on Japanese territory in the East China Sea, in its land building and potential military and naval bases in the South China Sea, it’s perceived as a threat."

Relations with South Korea are also shaky at the moment. As with China, the two countries have long-standing disputes over territory, and a relationship coloured by colonial history: the issue of Japan’s use of wartime ‘comfort women’, and other details of its war past, still loom.

Arms race
The celebrations of the 70th anniversary of the end of the Second World War in China saw a massive display of force in Beijing, with Xi Jinping pulling out all the stops to show that his nation is prepared for anything. In the context of these changes to Japan’s military, could an arms race could break out?

Japan’s self-defence forces are certainly getting an upgrade, particularly its navy. In March, the country brought into service its largest warship since the Second World War, the 814ft ‘helicopter destroyer’, which bore a striking resemblance to an aircraft carrier. And there’s a sister ship on the way. This year, the Japanese Ministry of Defence purchased 46 US F-35 jet fighters, increased the number of submarines from 16 to 22, and will begin upgrading its missile defence forces.

"I genuinely don’t know if we’ll see the beginning of an arms race," says Warren. "But there will be, I’m sure, a desire to increase capability and flexibility in ways that enable Japan to say, in the unlikely event of a confrontation, that they’ll be able to defend themselves."

Japan is spending more on its military than ever before. In August the defence ministry requested 5.09 trillion yen (£27 billion) for the financial year beginning April 2016. If approved, it’ll make Japan’s next military budget its biggest ever and it will increase by 2.2% year on year. It’s small fry compared with China’s military spending, which rose to £90 billion in 2015, but it’s a significant sign of a trend that’s sure to continue in the coming years.

Despite the discord in Japan about the merits of the changes to the constitution, the US and its NATO allies are and happy that in the face of China’s new ambitions, they have a dependable friend in the region.

"The Americans will welcome it," says Warren. "They approve of the burden sharing and they will approve of Japan playing a part in collective security. There are also South-East Asian countries, like the Philippines and Vietnam, which will welcome the possibility of Japan playing a more active role in regional security."

Shinzo Abe is bringing hard-headed realism to foreign and defence policy that for decades has mistaken the generosity of allies for the success of its idealism. The international order is reverting to the days of great-power politics, where military strength and strategic acumen, not diplomacy, are the tools of the trade. In this climate, it makes sense that Japan should take greater initiative in its own defence.

He’s commissioned various academics to look at the legislation and a number of them, including ones we thought were sympathetic to Abe, have come back saying ‘this infringes the constitution’.

It’s not necessarily as simple as that, however, and the issue of the role of the military in Japanese society is divisive. For the right, it’s made the country too reliant on the US to keep it safe, and limited its ability to project its stature abroad. From the point of view of the left, however, 70 years of a pacifistic constitution has served the country well, giving the nation a moral authority and protecting young soldiers from dying abroad.

"It plays into a sense of conflict within Japanese society," says Warren, conceding that the prime minister has not worked as hard as he can to convince the public about the merits of the new law.

"He hasn’t led a persuasive public debate on this – he’s commissioned various academics to look at the legislation and a number of them, including ones we thought were sympathetic to Abe, have come back saying ‘this infringes the constitution’."
So does it make the region more or less secure? It’s hard to say. With so much geopolitical uncertainty in east Asia, throwing a newly militarised Japan into the mix doesn’t seem to be a recipe for stability.

"I hope it will make the region more secure," says Warren. "It allows Japan to be clearer about its international obligations with its allies, and it seems to me completely compatible with what a liberal democracy should be able to do in terms of deploying its armed forces."

Whether Japan’s neighbours agree with Warren is another question.