Opinion | How Takaichi’s landslide victory will reshape China-Japan security

Japan’s House of Representatives election on February 8 delivered more than a decisive result. It produced a domestic political configuration with direct and lasting consequences for Sino-Japanese relations. The scale of the Liberal Democratic Party’s (LDP) victory under Prime Minister Sanae Takaichi has altered both Tokyo’s internal balance of power and the incentives shaping Japan’s strategic posture towards China.

The LDP secured 316 seats in the election, surpassing the two-thirds threshold on its own for the first time since World War II. With its coalition partner, the Japan Innovation Party, the ruling bloc now controls 352 seats. The opposition Centrist Reform Alliance has been reduced to the margins. This outcome grants the new administration an unusually strong mandate, a durable parliamentary base and broad freedom of action in economic, diplomatic and defence policy.

In practical terms, the supermajority removes many of the internal constraints that have traditionally moderated Japan’s security debates. Factional bargaining within the LDP, coalition compromises and the disciplining effect of a strong opposition will all carry less weight. The question is no longer whether Tokyo can act, but how far it will choose to go.

That question is particularly salient for China-Japan relations, which have already entered a period of strain. Since remarks made last year linking Japan’s security to a Taiwan crisis, bilateral relations have deteriorated. Takaichi has said Japan could not stand idly by if US forces were attacked in a Taiwan emergency without risking the collapse of the US-Japan alliance.

A supermajority lowers the political cost of assertive security legislation, weakens parliamentary oversight and rewards hardline positioning. Security policy becomes less contested domestically even as its external consequences grow more significant. The risk is that Sino-Japanese relations slide into a self-reinforcing security dilemma with diminishing space for correction.