Japanese Prime Minister Shinzo Abe has signalled his intention to reignite a long-running debate over revising the country's war-renouncing constitution, citing regional security concerns as one reason behind the push.

Speaking at an annual rally on constitutional revision organised by his own ruling party earlier this week, Mr Abe said the time had come "to show the people, with confidence, our vision for the future of [Japan] and what an ideal constitution should look like".

However the question of whether to reform the US-drafted document — which celebrates its 70th anniversary today — has been a highly divisive issue in Japan for almost as long as it has existed.

What's the big deal?

The constitution's most notable and controversial feature is Article 9, which officially prevents Japan from going to war, or maintaining an army of any kind.

Article 9: "Aspiring sincerely to an international peace based on justice and order, the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes."

"Aspiring sincerely to an international peace based on justice and order, as a sovereign right of the nation and the threat or use of force as means of settling international disputes." "In order to accomplish the aim of the preceding paragraph, land, sea, and air forces , as well as other war potential, will never be maintained ."

"In order to accomplish the aim of the preceding paragraph, , as well as other war potential, ." "The right of belligerency of the state will not be recognized."

While some Japanese think Article 9 should be updated to reflect the challenges the country now faces, including China's actions in the South China Sea and North Korea's nuclear ambitions, most do not want the pacifist spirit of the text to be altered, and some even fear what that change may bring.

On the more nationalist side, it's sometimes argued that the post-war constitution is a legacy of Japan's defeat in World War II, and that it imposed the United States' world order and values on the country.

Sorry, this video has expired Japanese PM flags new constitution debate

"This is still politically very charged, a very emotional issue for many people," said Yuki Tatsumi, a senior associate and director of the Japan program at the Stimson Centre in Washington DC.

"There are very, very vocal groups in Japan that strongly believe that if you touch one word in Article 9, that is the beginning of the slippery slope."

While Mr Abe is yet to shed light on what changes his government will specifically be pushing for, draft revisions released by his Liberal Democratic Party in 2012 included an emergency article and the right to self-defence.

But Ms Tatsumi doubts the policy of official pacifism will be changed.

"Proponents of the revision are really looking to make sure that what Article 9 says is a little bit more aligned to the reality that Japan has," she said.

Is now the right time?

While the article prevents Japan from maintaining an army, it still has a modern army of sorts in the form of the Japan Self-Defence Forces (JSDF), and Ms Tatsumi says providing clarity on this issue could be a focus of the debate.

However the role of the JSDF is itself controversial — laws passed by the Japanese parliament in 2015 that made it possible for the force to fight overseas sparked huge protests.

Ms Tatsumi said those recent security bills, which allowed for limited changes to how Article 9 is interpreted, may cause problems for Mr Abe on his quest for proper constitutional change.

The controversial security bills sparked large-scale protests in 2015. ( Reuters: Yuya Shino )

"In a sense, passing [the security bills] actually took some of the justification away from the Abe Government's strong desire to revise Article 9," she said.

"That legislation had actually taken care of the minimum that Japan would be needing to do both internationally but also in the region of contingencies, in support of US military operations.

"I'm doubtful that the Government has a strong case in trying to push the constitutional revision at this time."

Alternatively, in the face of increasingly bellicose rhetoric from North Korea, a growing sense of insecurity may shift the views of some people previously ambivalent about the constitution issue.

"When there's a clear and present security challenge — and you almost get exposed to that daily with North Korea's all kinds of crazy behaviour — you start thinking differently about your own safety and your own security," Ms Tatsumi said.

So it's just about security?

Well, that's where things get a little hairy.

Likely to muddy the waters of any debate is Mr Abe's link to the Nippon Kaigi, a ultra-nationalist lobby group that has been pushing to reform Article 9 for decades.

Mr Abe's connection to the group came under the spotlight most recently in March, when it was revealed that he and his wife were involved with an Osaka kindergarten set up by the Nippon Kaigi, where children are allegedly indoctrinated in nationalist principles.

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The head of the school was the leader of the Osaka branch of the Nippon Kaigi, and it has been alleged that he received government land for the kindergarten at a reduced rate.

Some members of the secretive organisation have a revisionist view of Japan's modern history — they see World War II as Japan's attempt at liberating East Asia, and deny some war-time atrocities committed by Japan.

While Mr Abe's connection to the group is public knowledge, Ms Tatsumi says the leader's approach to the constitution debate is likely to remain pragmatic.

"If [Abe] really wanted to ram through the constitutional revision, or much wider changes in the defence legislation, he had the numbers to do so … But at the end of the day he chose not to go that way," she said.

"[The Government is] sensing that there is this intangible red line that the Japanese public will not let the Government go over, and I think they will continue to stay within that boundary."

Ms Tatsumi says that 'red line' is whether to allow the JSDF to conduct the types of operations that the United States conducts in the Middle East, which may require them to use force.

"Japanese people have been quite proud that their defence forces have not had to fire a shot to kill the citizens of other countries up to this point, even with their participation in UN peacekeeping operations," she said

"I think they would very much like to continue to keep it that way."

ABC/AP