# Japan Weighs Defence Spending at 3.5% of Output as Long Bond Yields Sit at Multi-Decade Highs

A government adviser says the increase would be spread across a decade or more and should not unsettle markets in any single year.

- Published: 2026-09-28T05:13:14.945Z
- Canonical: https://polylog.news/2026-09-28/japan-weighs-defence-spending-at-3-5-of-output-as-long-bond
- Publisher: Polylog (Global desk)
- Section: macro
- Sources: [The Japan Times](https://www.japantimes.co.jp/business/2026/09/28/markets/defense-spending-no-market-anxiety/), [The Japan Times](https://www.japantimes.co.jp/news/2026/09/28/japan/us-typhon-missile-japan-storage-okinawa/), [Taipei Times](https://www.taipeitimes.com/News/front/archives/2026/09/16/2003864340)

Japan is considering a medium-term target to raise defense spending to 3.5% of gross domestic product over ten years, a level in line with what the United States has urged its allies to adopt. Takuji Aida, chief economist at Credit Agricole and a member of a panel advising Prime Minister Sanae Takaichi, said the increase would be spread over many years and [should not become a source of significant market anxiety](https://www.japantimes.co.jp/business/2026/09/28/markets/defense-spending-no-market-anxiety/) in any single year, describing it as a goal for the next ten to fifteen years.

Bond investors have already reacted. Reports that Tokyo was weighing the 3.5% figure [under American pressure](https://www.taipeitimes.com/News/front/archives/2026/09/16/2003864340) were followed by Japanese thirty-year yields reaching their highest level in three decades, [according to Eastern Herald](https://easternherald.com/2026/09/21/japan-defense-gdp-target-us-pressure-bond-yields/). Nikkei Asia has since reported that Takaichi has grown more cautious about committing to any output-share target.

The military buildup is proceeding regardless of how the spending target is framed. The Typhon midrange missile system, deployed to Japan for joint exercises, [will be stored indefinitely at Kadena Air Base in Okinawa from mid-October](https://www.japantimes.co.jp/news/2026/09/28/japan/us-typhon-missile-japan-storage-okinawa/). That is a concrete change in posture, and it is the kind of commitment that generates recurring budget obligations rather than one-off procurement.

The underlying tension is straightforward. Japan carries the largest government debt burden among advanced economies, the Bank of Japan is withdrawing from its policy of suppressing bond yields, and any durable increase in defense spending must be financed either through issuance into a market that has already repriced long-term debt higher, or through taxes that would slow the growth Takaichi has promised.

## What this means

The exposure sits in Japanese government bond duration and in the global positions financed with cheap yen. Long-dated Japanese debt has already repriced on the expectation of higher structural deficits, so holders of that debt lose further value as issuance plans become firmer, domestic banks and life insurers carry mark-to-market losses, and anyone funding foreign asset purchases in yen faces rising costs as the currency's interest-rate discount narrows. Takaichi wants growth and an alliance commitment simultaneously, her advisers are managing market expectations by stretching the timeline, and the binding constraint is the price the long end of the bond market demands. The precedent is the September repricing itself, when a single press report about the target moved thirty-year yields to a three-decade high without any legislated spending. The likelier outcome over coming months is a target announced with a long horizon and a deliberately vague annual profile, which limits the headline risk without resolving the financing question, and long yields continue drifting higher. Evidence against this read would be a firm tax-funded financing plan accompanying the target, or Takaichi abandoning the output-share framing entirely.

## What to watch

- Whether the government attaches an annual spending path to any target, because a vague horizon and a dated schedule have very different effects on bond supply expectations.
- Japanese thirty-year yields around the next long-dated auctions, the direct measure of whether investors will fund the plan.
- Further American requests tied to basing and equipment, such as the Typhon storage decision, which create obligations before any budget target is legislated.