Former Bank of Japan chief economist Toshinao Sekine believes that market bets on a potential Bank of Japan rate hike in October underestimate the uncertainty brought by Trump's tariff measures.

"What I want to say is that the uncertainty is greater than market participants might think," Sekine said in an interview in Tokyo. "If you ask me to determine the potential impact of tariffs in October, I would say 'no'."

As Japan's economic resilience becomes apparent, some economists have identified October as the most likely timing for the Bank of Japan's next rate hike. Sekine said he does not completely rule out the possibility of a rate increase, as a range of factors including exchange rates will influence the decision. However, it would be difficult to claim at that point that economic risks have sufficiently receded.

"The Trump administration's measures are confrontational and unpredictable, to the point where I almost don't want to watch the news," said Sekine, who now serves as an economics professor at Hitotsubashi University. "Markets can make mistakes, and that's fine; but monetary policy cannot. Policy cannot be changed so easily."

The former central bank official referenced the Bank of Japan's history in the first decade of this century, when rate hikes and exit from easing policies were widely criticized as premature. In hindsight, the economy was still deeply mired in deflation.

Bank of Japan Governor Kazuo Ueda has already promised to closely monitor the impact of U.S. tariffs. The market widely expects the central bank to maintain rates at 0.5% at the policy meeting ending on September 19.