Japan's Prime Minister Shinzo Abe has had his way by ramming through key legislation that would permit his forces to fight overseas for the first time since World War II.

The move is clearly unpopular with large sections of his people, including the young, who were generally considered apathetic to politics.

That Mr Abe chose to ignore his sliding ratings to push the Bills, and that his Liberal Democratic Party stands unflinchingly with him, speak both for the seriousness of his resolve and his grip on his party.

There was similar opposition when Japan joined United Nations peacekeeping operations in 1992, and when it sent troops to Iraq in 2004 for construction projects. Nevertheless, Mr Abe must have spent the weekend grateful that he is not Australian.

China's negative reaction, and the overt and unspoken endorsement of his actions by several other Asian powers, speak for Asia's current preoccupations where Beijing's assertive posture under President Xi Jinping is wrinkling brows.

The China factor, alongside his personal reluctance to cede Japan's dominance of Asia, are no doubt his principal motivations, besides worry that United States commitment to Japan's security may wane in future.

But there is another unspoken issue: fear of a unified Korea and, should that happen, the unpredictability of its strategic direction. Notably, South Korean President Park Geun Hye was a rare US ally to turn up for China's impressive military parade marking victory over Japan.

Mr Abe could have helped his cause with an unequivocal apology for Japan's wartime atrocities. That he did not do so, even as he called his predecessors' apologies "unshakeable", speaks of poor statesmanship. Mr Xi also missed an opportunity to project China's greatest post-war achievement - raising 500 million people from poverty.

Mr Abe can now focus on the economy. More than his troops, Asia needs its No. 2 economy to be healthy for its wider security.