The Bank of Japan is responsible for deciding whether to ramp up stimulus to support the economy, but should weigh the impact its monetary policy will have on the banking sector, the country’s top financial regulator said on Monday.

There is mounting speculation the BOJ may be forced to join other major central banks in expanding stimulus as early as next month to protect economic growth as the U.S.-China trade war continues to drag on Japan’s export-reliant economy.

Toshihide Endo, commissioner of the Financial Services Agency (FSA), said sliding global bond yields and the BOJ’s prolonged ultra-loose monetary policy were only among various factors weighing on regional banks’ profits.

Structural woes, such as a shrinking population, were also exerting pressure on Japan’s regional banks to revamp their business models into those less reliant on traditional lending, Endo said.