As east Asia’s leading nations talk tensely of war and peace, critics of Shinzo Abe, Japan’s pugnaciously conservative prime minister, say it is his brand of unrepentant, right-wing nationalism that has helped push the region to the brink. His supporters say Abe is rightly, finally standing up for Japan.

How Abe might react if China’s unilaterally imposed “air defence zone” over the Senkaku islands in the East China Sea triggers armed clashes is a serious international concern. The US is pledged to come to Japan’s aid should it be attacked, while hardliners in China’s military leadership would welcome a fight over what they call “core interests”. There is potential for a head-on superpower collision.

Since taking office as prime minister for the second time a year ago, stocky, tousle-haired Abe, 59, has avoided hot-headed actions and kept his political powder dry. But he is no patsy, either. Nobody knows for sure which way he may jump, if push comes to shove.

“Abe is very rightwing by traditional measures,” said Akio Takahara, professor of international relations and law at Tokyo University, which makes him a potentially dangerous figure. “He is a historical revisionist at heart. He is a nationalist [pursuing] his ‘new nationalism’.”

In this sense, Takahara suggested, Abe was a throwback to Japan’s past, and thus an obstacle to the sort of calm dialogue needed in dealing with China.

Not so, said Yoshiji Nogami, a former Japanese ambassador to Britain who has known Abe personally for many years. “He is, first and foremost, a politician and a politician’s instinct is to survive. As his first premiership ended in such a disastrous way, he is determined to stay this time.

“In order to stay in power for a long period of time, I believe he can be flexible. He is not an ideologue. He is certainly a conservative, a nationalist and right of centre, but he is not an ideological right-winger,” Nogami said.

The research director of a leading Tokyo think tank offered a third perspective: “I would call him one of a new kind of very conservative, patriotic politicians who are not always happy with post-war Japan’s traditional, leftwing internationalists and their strong tendency towards irresponsible pacifism.”

In short, he said, Abe was saying it was time for Japan to stand up for itself, that it was “OK to be proud” again.

Dangerous militarist or modernising reformer, Abe’s career has rarely lacked controversy. Born in Sept 1954 to an affluent and influential family, he became Japan’s youngest-ever prime minister in 2006 and the first to be born after the end of the second world war.

Elected to parliament in 1993, Abe was later selected to work for the popular prime minister Junichiro Koizumi.

His continuing interest in reinterpreting Article 9 of Japan’s pacifist constitution, to allow the country to develop its military might unchecked, is seen as similarly inflammatory by the Chinese and Koreans, and further proof of his revisionist views. So, too, is his creation of a Restoration of Sovereignty Day, an annual event to mark the end of the American occupation.

Abe would doubtless like to suggest that, like Japan, he has changed as time has passed. His first term, 2006-7, was marred by Liberal Democratic Party scandals, including a ministerial suicide, leading to his forced resignation on health grounds. This time around, he has eschewed social policy controversies and moved cannily to broaden his base support while pursuing a radical economic plan and an ambitious foreign policy agenda.

Abe’s initial success in boosting Japan’s economic fortunes has proven a necessary precondition for advancing his autonomous global agenda.

In a speech to the UN general assembly in September, Abe vowed to make a revitalised Japan “a force for peace and stability” in the world, while putting China on notice that coercion would not work.

Abe has also skilfully exploited the China problem to woo less-powerful neighbours. Since taking office Abe has visited all 10 members of the Association of South-East Asian Nations (Asean), an unprecedented piece of outreach by a Japanese leader. Last weekend he hosted an Asean summit in Tokyo marking 40 years of diplomatic ties.

In a classic soft-power exercise that totally outflanked Beijing, Abe ordered the biggest overseas deployment of Japanese armed forces since 1945, backed by generous donations, to assist the Philippines after last month’s super-typhoon disaster.

Scarred by his first experience as prime minister, Abe seems determined to stick to a cautious line, avoid repeating past mistakes and stay the course to 2015. Economic recovery remains his top priority.

But for a man of strong and passionate views, this restraint seems unnatural and may not be sustainable. International tensions may yet stir his blood and force his hand. Just how long he can — and wants to — keep a lid on the confrontation with Beijing, as China inexorably ups the ante, is east Asia’s big unanswered question of 2014. —By arrangement with the Guardian