E.C.B. Cuts Interest Rates Again, With an Uncertain Path Ahead

The European Central Bank lowered interest rates on Thursday, the sixth consecutive cut, as the economic landscape for the region rapidly changes.

The bank’s key rate was cut by a quarter point to 2.5 percent, which was widely expected as inflation in the region has stayed relatively low and economic growth has been weak.

But the future path of interest rates has become increasingly uncertain as policymakers face a seismic shift in Europe. In the past few days, European leaders have vowed to increase military spending by hundreds of billions of euros as they are no longer sure of their alliances with the United States. A decade and a half of strict fiscal constraint in Germany is being broken as the country’s next government is planning to ease borrowing rules to allow more spending on defense and infrastructure.

On Thursday, Christine Lagarde, the president of the central bank, emphasized the whirlwind pace of economic and political change taking place in Europe.

“We have not been spared recent developments in the last few hours and days,” she said at a news conference in Frankfurt.

Ms. Lagarde said policymakers would be “attentive” and “vigilant” to those spending plans to determine the effect on inflation. But she added that officials at the bank expected the additional spending to add to economic growth. She added that policymakers were keenly following developments in Brussels on Thursday, as European leaders gathered to negotiate defense plans.