Former Treasury Secretary Lawrence Summers said the Federal Reserve’s decision to dramatically slow down the shrinkage of its US Treasuries holdings amounts to a worrying signal about market demand for longer-term federal debt.

The Federal Reserve’s policy committee announced it would slow the pace of reducing its balance sheet starting in April. Wednesday’s statement also highlighted the increased uncertainty for the economy.

After the Federal Reserve moved to slow the pace of quantitative tightening, the Fed chair floated the idea of continuing to allow mortgage-backed securities to roll off its books even after the central bank has met its monetary policy objectives in reducing its balance sheet.