Rising government borrowing costs are complicating the Bank of Japan’s path toward higher interest rates as fiscal expansion, inflation and investor unease collide.

Japan is entering a delicate new phase in its economic normalization, as rising government-bond yields expose growing tension between the Bank of Japan’s efforts to move away from years of ultra-loose monetary policy and the government’s ambitions to support growth through aggressive fiscal spending.

The yield on Japan’s benchmark 10-year government bond climbed to 2.805% on Monday, moving closer to the 3% level that some analysts believe could trigger renewed selling pressure in the country’s enormous sovereign-debt market. The rise reflects increasing investor concern over the scale of Prime Minister Sanae Takaichi’s expansionary fiscal agenda and the implications it could have for government borrowing.

The development is particularly significant because Japan carries one of the largest public-debt burdens among advanced economies. Even relatively modest increases in borrowing costs can therefore translate into substantially higher debt-servicing expenses, potentially limiting the government’s ability to finance future stimulus, social spending and infrastructure investment.

At the same time, the Bank of Japan is attempting one of the most difficult monetary-policy transitions in the global economy. After years of negative interest rates, large-scale bond purchases and direct intervention in the yield curve, the central bank has been gradually withdrawing extraordinary support and allowing market forces to play a larger role in determining borrowing costs.

The BOJ ended its yield-curve-control framework in 2024 and subsequently began reducing the scale of its government-bond purchases. Policymakers have increasingly argued that Japan must restore a more conventional monetary framework now that inflation has become more persistent and wage growth has improved.

That transition, however, is becoming more complicated.

Rising yields reflect both expectations of further BOJ interest-rate increases and investor concern over government fiscal policy. Prime Minister Takaichi has maintained an economic approach influenced by the expansionary philosophy associated with former premier Shinzo Abe, favoring government support for growth and resisting an excessively rapid withdrawal of monetary accommodation.

The tension creates a difficult balancing act. If the Bank of Japan raises rates too quickly, it risks increasing financing costs for households, companies and the government. If it moves too slowly, inflationary pressure could remain elevated and investors could lose confidence in the central bank’s commitment to maintaining price stability.

The problem is particularly acute in the bond market. Large-scale purchases by the BOJ dominated Japanese government bonds for years, suppressing yields and reducing market liquidity. As the central bank gradually withdraws, private investors are being asked to absorb a larger share of government issuance at a time when concerns about fiscal sustainability are intensifying.

Some former policymakers have warned that renewed large-scale bond purchases would create additional risks. If markets concluded that the Bank of Japan was buying government debt primarily to prevent borrowing costs from rising, the move could be interpreted as a form of fiscal dominance, weakening confidence in the central bank’s independence.

That risk explains why BOJ officials have repeatedly emphasized that additional bond purchases would be used primarily as an emergency tool if market movements became disorderly or threatened financial stability, rather than as an instrument for maintaining permanently low government borrowing costs.

The central bank has also argued that rising inflation, rather than the reduction of its bond purchases alone, has been a major driver of higher long-term interest rates. Minutes from its June policy meeting showed policymakers discussing the eventual size of the BOJ’s balance sheet, suggesting that the institution remains committed to gradually reducing the extraordinary monetary footprint accumulated over decades.

Japan’s economic dilemma also has international implications. Japanese investors are among the world’s largest holders of overseas financial assets, including U.S. Treasuries and European government debt. As yields rise at home, Japanese institutions may find domestic bonds increasingly attractive, potentially encouraging the repatriation of capital previously invested abroad.

Such a shift could affect global bond markets by reducing Japanese demand for foreign government securities and contributing to upward pressure on borrowing costs elsewhere.

Currency markets are another important part of the equation. Expectations of higher Japanese interest rates have already altered perceptions of the yen, while investors remain sensitive to the possibility of government intervention if currency movements become excessively volatile.

For Tokyo, the broader challenge is ultimately structural. Japan spent decades attempting to escape deflation through extremely low interest rates, aggressive bond purchases and fiscal stimulus. The country is now confronting almost the opposite problem: how to manage an economy in which inflation, wages and interest rates are once again moving upward without destabilizing a financial system built around exceptionally cheap money.

The transition will require unusual coordination between fiscal and monetary policymakers. The government wants sufficient economic support to sustain consumption, investment and wage growth, while the Bank of Japan needs to demonstrate that inflation can be controlled without permanently financing government borrowing.

The rise in Japanese bond yields therefore represents more than a routine market movement. It is becoming a test of whether the world’s fourth-largest economy can successfully leave behind the extraordinary monetary policies that defined Japan for much of the past three decades.

The answer will have consequences well beyond Tokyo. If Japan manages the transition smoothly, it could mark the final stage of its long battle against deflation. If borrowing costs accelerate faster than policymakers can control, however, Japan’s enormous debt burden could transform monetary normalization into one of the most consequential economic challenges facing Asia.