The Swiss National Bank cut its interest rate to zero on Thursday and did not rule out returning borrowing costs to negative territory in future, although it stressed this was not a step it would take lightly.

Switzerland cut rates to zero to rein in the rapidly appreciating franc, which has acted as a safe haven for investors given raised concerns over U.S. trade policy and Middle East tensions.

Switzerland’s central bank says it has cut its target interest rate by a quarter of a percentage point, adding inflationary pressures have eased.