Japan defence build-up ‘critical’ to prevent war, says Koizumi

Japan’s Defence Minister Shinjiro Koizumi has told the BBC that accelerating the country’s military expansion is essential to keeping the peace in Asia, making the case that Tokyo can no longer rely on the pacifist constitution that has shaped its security posture for nearly eight decades.

A break from the past

Speaking in an interview broadcast on Tuesday, Koizumi was direct. Japan must move beyond the restraint imposed after World War Two, he argued, because the threat environment in the Indo-Pacific has fundamentally changed. China’s military spending has grown for 29 consecutive years. North Korea fired more than 40 ballistic missiles in 2022 alone. And Russia’s invasion of Ukraine, Koizumi said, proved that aggression is not a relic of history.

‘The best way to prevent war is to show that Japan has the capability and the will to defend itself,’ he told the BBC. ‘That’s not a contradiction of peace. That is how you protect it.’

Billions earmarked for rearmament

Japan’s government approved a defence budget of roughly 7.7 trillion yen — around $52 billion — for the fiscal year starting April 2025. It’s part of a five-year plan to double defence spending to two percent of GDP by 2027, a target that would bring Japan in line with NATO guidelines and represent the most dramatic military investment the country has seen since 1945.

The money is funding new long-range cruise missiles, advanced radar systems and a significant expansion of the Japan Maritime Self-Defense Force. Tokyo has also agreed to buy up to 400 Tomahawk missiles from the United States.

Koizumi didn’t shy away from the political sensitivity of all this. Japan’s pacifist Article 9 constitution, written under American occupation after the war, prohibits the country from using force to settle international disputes. Reinterpreting — rather than formally amending — that article has allowed successive governments to expand Japan’s military role incrementally. But critics, including some within Japan, say the current trajectory is pushing the boundaries of what that constitution permits.

Regional tensions driving urgency

The backdrop is impossible to ignore. Taiwan sits roughly 110 kilometres from Japan’s southernmost islands. A Chinese military takeover of Taiwan would almost certainly draw American forces into conflict — and American bases in Japan into the line of fire.

Japan can’t afford to be a bystander in that scenario, senior officials in Tokyo have made clear.

A defence analyst familiar with the ministry’s planning told reporters last month that the speed of Japan’s military modernisation has surprised even close allies. ‘They’re moving faster than anyone expected,’ the analyst said. ‘The political will is there in a way it wasn’t five years ago.’

What comes next

Koizumi is widely expected to play a significant role in shaping Japan’s security policy in the years ahead, potentially including a run for party leadership. His willingness to speak bluntly about rearmament on an international platform signals that Tokyo is no longer interested in quietly managing its military expansion. It wants the world to notice.