Federal Reserve Chairman Jerome Powell waded gingerly into the debate over tariffs, saying that countries embracing protectionism fare worse than those that are more open.

Asked during Senate testimony Tuesday about what impact tariffs have on growth, the central bank chief did not directly address policies that have led to a burgeoning global trade war.

However, he did speak in general terms and said the prognosis for protectionism is generally not good.

"In general, countries that have remained open to trade, that haven't erected barriers including tariffs, have grown faster, they have higher incomes, higher productivity," Powell said. "Countries that have gone in a more protectionist direction have done worse. I think that's the empirical result."

Trade has become one of the big hot-button issues for the economy in 2018.