Federal Reserve Chairman Jerome Powell is leading his colleagues to cut interest rates this week for the first time since 2008, even though the economy looks healthy, partly because it isn’t behaving as expected.

Both inflation and market-determined interest rates are still lower than some of their models would have forecast, given years of strong hiring and solid economic growth.

These developments suggest that Fed officials haven’t been providing as much support to the economy as they had thought, even though their benchmark rate is low by historical standards.

Moreover, some officials believe the rate needs to be even lower now to provide an extra cushion amid a darkening global outlook clouded by trade-policy uncertainty.

Fed leaders see tighter linkages than in the past between the U.S. and global economies and think domestic rates can’t rise much higher above those in other advanced economies, which have much lower or even negative rates.